# Do Healthy Plants Release Organics?



## jaypeecee (28 Nov 2019)

Hi Folks,

I am trying to get a full(er) picture of what contributes to dissolved organic carbon (DOC) in freshwater aquariums. Why? Well, I still have an ongoing problem with an oily film on the water surface. Using the kitchen paper towel method is effective but the result is short-lived. I syphon the substrate, I don't over-feed my fish and I use organic waste removal media in my external filter. The filter is cleaned monthly. If all else fails, I'll resort to a surface skimmer but I'd rather deal with the root cause.

Unhealthy, decomposing plants will obviously contribute to DOC. I do believe that healthy plants must also contribute to DOC. Otherwise, I presume that allelopathy couldn't occur. So, do healthy plants release organics (into the water column)? And, would this be sufficient to contribute to the formation of surface films?

JPC


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## Edvet (28 Nov 2019)

jaypeecee said:


> use organic waste removal media


Which? and why?


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## dw1305 (28 Nov 2019)

Hi all, 





jaypeecee said:


> I do believe that healthy plants must also contribute to DOC





jaypeecee said:


> So, do healthy plants release organics (into the water column)?


I think they do, plants are generally pretty leaky structures.

Somewhere there is a <"more thorough post, than this one">* by Clive @ceg4048,  or Tom Barr @plantbrain, that says the reason for the 50% water change when you use EI is as much to remove DOC as to remove any excess of ions. 





ceg4048 said:


> .......We should remember that in high growth closed systems, with no avenue of escape, complex organic molecules such as enzymes, proteins, lipids and so forth build up to levels which are not normally found in such high concentrations in naturally occurring open systems. Perhaps the marine folks are more tuned into this fact as they have lots of gadgets to remove organic waste (such as protein skimmers for example.) The effects of the organic compound buildup over time are varied but one thing is certain, they are normally precursors to ammonia production.........



Edit: * Possibly this one <"Water flow......">

cheers Darrel


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## Fisher2007 (28 Nov 2019)

What foods are you feeding?

Until recently I ran two planted low tech tanks and didn't struggle with oily film.  Neither had a surface skimmer

In my first marine system I used to suffer from an oily film though.  This tank didn't have a sump and so the surface wasn't being skimmer via the outlet/downpipes.  I did have a protein skimmer though and probably 25x plus turnover as well but even then this still didn't help.  What I did notice though was depending on what I fed it influenced the amount and density of the film, with frozen foods being the worst for it, hence the question


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## dw1305 (28 Nov 2019)

Hi all, 





Fisher2007 said:


> What I did notice though was depending on what I fed it influenced the amount and density of the film, with frozen foods being the worst for it, hence the question


I think certain foods have this effect. I mainly feed live food and very rarely have any surface film. 

cheers Darrel


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## jaypeecee (28 Nov 2019)

Thanks, everyone. Some very useful feedback there - especially about the types of food to feed. As a result of your feedback, I'm going to dig into the feeding thing in more detail. In the first instance, I'll check the composition of the foods that I currently use. Currently, I'm not feeding any live foods. The nearest I get to that is frozen bloodworm. Almost 100% of what I feed comes out of a tub. For example, Bug Bites, Seachem flakes and TMC Gamma pellets. @dw1305, would I be right in thinking that you probably feed Daphnia? And thanks for the comment about plants being "generally pretty leaky structures". Plus, the statement that "the reason for the 50% water change when you use EI is as much to remove DOC as to remove any excess of ions".

JPC


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## dw1305 (28 Nov 2019)

Hi all, 





jaypeecee said:


> I be right in thinking that you probably feed Daphnia?


Mainly _Daphnia_, Grindal worms and Micro worms  with some Black worms, _Crangonyx, _Aphids and Sciarid flies at the moment. In the summer there would be a bit more variety with Mosquito larvae and Blood worms added in. In amongst the Daphnia there would be some Copepods and Ostracods.

I usually have a vestigial winged fruit fly culture as well, but I don't have one at the moment (hence the Aphids and Sciarid flies).

Dried food I've got "Freeze Dried Arctic Copepods" and "TA Blend no.1" from <"TA Aquaculture">. I might try the <"Artemisia Soft Pellet"> next time I buy some dry food.

cheers Darrel


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## jaypeecee (29 Nov 2019)

dw1305 said:


> Mainly _Daphnia_, Grindal worms and Micro worms  with some Black worms, _Crangonyx, _Aphids and Sciarid flies at the moment. In the summer there would be a bit more variety with Mosquito larvae and Blood worms added in. In amongst the Daphnia there would be some Copepods and Ostracods.
> 
> I usually have a vestigial winged fruit fly culture as well, but I don't have one at the moment (hence the Aphids and Sciarid flies).



@dw1305 - lucky fish! BTW, the link to TA Aquaculture is handy. You may also be interested in https://www.zmsystems.co.uk.

JPC


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## dw1305 (29 Nov 2019)

Hi all, 





jaypeecee said:


> You may also be interested in https://www.zmsystems.co.uk.


Yes, that is the one that the University use when they work with Zebra "Fish" (_Danio rerio_), I'm not sure I can afford them. 





jaypeecee said:


> the link to TA Aquaculture is handy


I don't get through much dry food, but I've traditionally bought my food from them. 

Tim (Addis) has a Facebook page as well, that is where the link to this video came from.



cheers Darrel


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## Iain Sutherland (29 Nov 2019)

Im yet to see or keep a high tech tank that doesnt have a surface film.  If you look at ADA gallery, Green aqua gallery, aquarium gardens or any high end outlet that keep multiple tanks to see that every tank runs a surface skimmer of some kind.  Obviously tanks that run overflow systems are excluded from this.

Low tech it really isnt an issue (aside high feeding levels and poor maintenance) but put high energy on a tank and DOC increases to a point that surface agitation doesnt seem to cut it.


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## Tim Harrison (29 Nov 2019)

It's pretty much a fact of life with planted tanks, healthy or otherwise. I once had a surface film as thick as treacle in a newly planted tank. Even strong surface movement did little to disperse it, it all just wrinkled up at one end like Nora Battey's tights. Other than that the tank was a great success, so it's not necessarily a sign that something is wrong...

Just get one of these...


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## jaypeecee (30 Nov 2019)

Iain Sutherland said:


> Low tech it really isnt an issue (aside high feeding levels and poor maintenance) but put high energy on a tank and DOC increases to a point that surface agitation doesnt seem to cut it.



Hi @Iain Sutherland

That's _really_ useful feedback. Combining the comment by @dw1305 that "plants are generally pretty leaky structures" with your statement above, I conclude that, in the 'high tech' environment, it is most likely the plants that are causing the surface film. If that's the case, then the surface film cannot be prevented - or can it? (see my next post). Thus, the only option is to do what @Tim Harrison is suggesting, i.e. use a surface skimmer. As it happens, I have ordered an Eheim skim 350, which should arrive today.

JPC


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## jaypeecee (30 Nov 2019)

Hi Folks,

If the root cause of the surface film is DOC produced by the plants, is it not possible to use activated carbon, Seachem _Purigen_, etc. in an external filter to remove these dissolved organics? Surely, that ought to be a possibility? I would have preferred this approach in order to eliminate another piece of equipment inside the tank itself. I consider the surface skimmer to be a last resort. I don't think dissolved organics get enough attention on freshwater aquarium forums/fora.

JPC


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## dw1305 (30 Nov 2019)

Hi all, 





jaypeecee said:


> is it not possible to use activated carbon, Seachem _Purigen_, etc. in an external filter to remove these dissolved organics? Surely, that ought to be a possibility?


I think the issue is probably the lipid and wax component, it floats and will combine (both physically and chemically) with <"proteins, complex carbohydrates etc">.  This layer then supports bacteria, fungi etc. 

This surface dwelling microscopic community has a scientific name, it is the "neuston".

I think the main issue is that it  would only need a small amount of lipids to cover the entire water surface, in a one molecule thick layer. You can't set the intake of a conventional filter to skim the surface, the filter will fill up with air, and protein skimmers don't really work in freshwater (it isn't dense enough), so that really just leaves a surface skimmer as an option, if you don't have a weir/sump setup.

I've never really suffered from it, but all my tanks have Tadpole and Ramshorn snails which are often "surf", between the floating plants, and may consume the surface layer quickly enough so that it never becomes too visible. The mechanism for Apple Snails feeding on the surface film is called "pedal surface collecting", but I don't know if smaller snails have the same adaptations. 

cheers Darrel


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## MJQMJQ (30 Nov 2019)

jaypeecee said:


> Hi Folks,
> 
> If the root cause of the surface film is DOC produced by the plants, is it not possible to use activated carbon, Seachem _Purigen_, etc. in an external filter to remove these dissolved organics? Surely, that ought to be a possibility? I would have preferred this approach in order to eliminate another piece of equipment inside the tank itself. I consider the surface skimmer to be a last resort. I don't think dissolved organics get enough attention on freshwater aquarium forums/fora.
> 
> JPC


Yep darrel is right.DOC will stain the water darker and is released by decaying organics.Plants need the carbon to grow so Im guessing it will not release it into the water.Prob to do with excess lipid production temperatures can also affect these things.Different species also have varying production.From what I know terrestrial species produce root exudates to form beneficial relations with fungi and bacteria.


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## MJQMJQ (30 Nov 2019)

jaypeecee said:


> Hi @Iain Sutherland
> 
> That's _really_ useful feedback. Combining the comment by @dw1305 that "plants are generally pretty leaky structures" with your statement above, I conclude that, in the 'high tech' environment, it is most likely the plants that are causing the surface film. If that's the case, then the surface film cannot be prevented - or can it? (see my next post). Thus, the only option is to do what @Tim Harrison is suggesting, i.e. use a surface skimmer. As it happens, I have ordered an Eheim skim 350, which should arrive today.
> 
> JPC





dw1305 said:


> Hi all, I think they do, plants are generally pretty leaky structures.
> 
> Somewhere there is a <"more thorough post, than this one">* by Clive @ceg4048,  or Tom Barr @plantbrain, that says the reason for the 50% water change when you use EI is as much to remove DOC as to remove any excess of ions.
> 
> ...


Well I like to think that they are selectively leaky to benefit themselves eg releasing co2 during respiration as byproduct because they dont need it clogging up their transport system.Its like say u can transport only 1000 units of goods, would u choose to transport co2 if it is useless and u need oxygen?


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## jaypeecee (30 Nov 2019)

Hi Folks,

I installed my new Eheim skim 350 today and it has now been running for several hours. It has made an improvement but there still appears to be a thin oily layer on the water surface. Having thought about how this surface skimmer works, I can't see how it can be fully effective. The sponge inside the skimmer has a coarse structure. I would estimate the 'pore' size to be about 1mm. It is just a simple, tiny synthetic sponge with no obvious impregnation. How can such simple filtration media trap anything other than particulate matter? Wouldn't carbon-impregnated foam be a better choice? I guess it would still need to be a coarse foam so as not to impair the suction.

JPC


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## MJQMJQ (1 Dec 2019)

jaypeecee said:


> Hi Folks,
> 
> I installed my new Eheim skim 350 today and it has now been running for several hours. It has made an improvement but there still appears to be a thin oily layer on the water surface. Having thought about how this surface skimmer works, I can't see how it can be fully effective. The sponge inside the skimmer has a coarse structure. I would estimate the 'pore' size to be about 1mm. It is just a simple, tiny synthetic sponge with no obvious impregnation. How can such simple filtration media trap anything other than particulate matter? Wouldn't carbon-impregnated foam be a better choice? I guess it would still need to be a coarse foam so as not to impair the suction.
> 
> JPC


Yep activated carbon impregnated foam or polyurethane foam will absorb the oils.It works by absorbing them.Is the foam polyurethane foam?


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## dw1305 (1 Dec 2019)

Hi all, 





MJQMJQ said:


> I like to think that they are selectively leaky to benefit themselves


Yes, they need dissolved gases and ions to  pass in and out of the plant through the epidermis. Even though a lot of aquatic plants don't have stomata they are still leaky structures.





MJQMJQ said:


> I know terrestrial species produce root exudates to form beneficial relations with fungi and bacteria.


Yes, research (a lot of it on Rice) has shown In roots the plant can change the composition of the exudates to manipulate the biotic and abiotic environment in the rhizosphere.  





MJQMJQ said:


> to benefit themselves eg releasing co2 during respiration as byproduct because they dont need it clogging up their transport system.Its like say u can transport only 1000 units of goods, would u choose to transport co2 if it is useless and u need oxygen?


 The CO2 is never actually a waste product, even when there is an excess of it during the dark period. Plants are very good at sequestering both the spare oxygen from photosynthesis and the CO2 respiration for use in the reciprocal process.

Plants are actually much more interested in removing "waste" oxygen, there are two reasons for this, one is that high levels of oxygen inhibit photosynthesis, and the other is that plants are massively net oxygen producers. One molecule of oxygen is evolved for every molecule of CO2 incorporated during photosynthesis, but plants are carbon based and their growth records that difference between CO2 incorporated and evolved.

cheers Darrel


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## Oldguy (1 Dec 2019)

jaypeecee said:


> with an oily film on the water surface.



Some very interesting information and opinions on this thread. I have found the effectiveness or otherwise of a surface skimmer to be related to surface area  proportions. In general if the tank is linear/rectangular and long form, skimmers are less effective that if the surface is square. I use a very under powered a.n.other skimmer to great effect with a cubic tank.

The coarseness of the filter material was at first disconcerting but I think its the biofilm that grows on the media that does the work and not mechanical filtration.

As to the origin of the film I would suggest lipids** from the plants and from flake food. These as at @dw1305  entrap proteins and feed microorganisms.



dw1305 said:


> "pedal surface collecting"



In natural waters you can see snails grazing the the under surface of the water. I also seem to remember  guppies and sword-tails vaccing the water surface.

In natural waters dull films are considered natural* and refractive films are considered to be hydrocarbons from run off.

* Not that natural when heavy rains have caused septic tanks to overflow into no perceptible flow watercourses. It can also occur from vegetable cooking oils** again from septic tank overflows.


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## jaypeecee (1 Dec 2019)

MJQMJQ said:


> Yep activated carbon impregnated foam or polyurethane foam will absorb the oils.It works by absorbing them.Is the foam polyurethane foam?



Hi @MJQMJQ

I'm not sure whether it's polyurethane foam or some other polymer. Sorry to be pedantic but I would have thought carbon-impregnated foam would a*d*sorb oils as opposed to a*b*sorb them. But, perhaps I'm wrong. That aside, you are obviously thinking on the same lines as me. Are you suggesting that polyurethane foam would work on its own, i.e. without carbon impregnation?

JPC


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## Iain Sutherland (1 Dec 2019)

I dont know if the carbon theory stands up... only on the basis that ADA superjet filters run only carbon as media, in the bigger ones several kgs, yet they still have skimmers running in all tanks in the ada gallery.

It's weird you still have film after running the skimmer, even on my bigger high tech tanks all film would be gone in 15 minutes? 
If you mean that you turn the skimmer off and it comes back in an hour or so then that's different.
The skimmer wont get rid of all surface scum as such, more that it keeps it in solution... the sponge does catch the initial film..  if you pull it out after 5 minutes you'll see the little sponge can have a white slime over it which is worth washing but leave it running and that slime will go back into solution.

Sent from my SM-G950F using Tapatalk


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## jaypeecee (1 Dec 2019)

Iain Sutherland said:


> It's weird you still have film after running the skimmer, even on my bigger high tech tanks all film would be gone in 15 minutes? If you mean that you turn the skimmer off and it comes back in an hour or so then that's different. The skimmer wont get rid of all surface scum as such, more that it keeps it in solution... the sponge does catch the initial film..  if you pull it out after 5 minutes you'll see the little sponge can have a white slime over it which is worth washing but leave it running and that slime will go back into solution.



Hi @Iain Sutherland

I just need to get used to this piece of kit. It's further complicated by the fact that I had to make a 'livestock protector'. I am fully aware that some people have had problems with the Eheim skim350 as it can suck in small fish, shrimps, etc. I am less than happy with some aspects of the mechanical design of this surface skimmer. But, it's probably the best of the bunch. My 'livestock protector' is a simple piece of plastic with many small holes in it. This does affect the flow - but only slightly. But, it's essential. One of my Panda Garras swam straight through the grooves in the skim350 floating structure. And that's a Panda Garra - approx. 6mm width!

After playing about with this skimmer today, it sucked in the entire surface film in less time than it has taken me to write this post! So, like I said initially, I just need to get used to it.

JPC


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## jaypeecee (1 Dec 2019)

MJQMJQ said:


> DOC will stain the water darker and is released by decaying organics.



Hi @MJQMJQ 

I thought tea-stained water was caused by humic substances (HS). But there are many other compounds relevant to aquarists under the heading of DOC, aren't there? In a quick search online, I found the following:

https://www.hindawi.com/journals/jchem/2016/1537370/

It goes well over my head but it may mean more to @dw1305 .

JPC


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## MJQMJQ (2 Dec 2019)

jaypeecee said:


> Hi @MJQMJQ
> 
> I thought tea-stained water was caused by humic substances (HS). But there are many other compounds relevant to aquarists under the heading of DOC, aren't there? In a quick search online, I found the following:
> 
> ...


Humic substances contain many different substances some of which is DOC/DOM eg humic acid. The ones that contribute to the colour are tanninc acids humic acids and other such HS.Yes there are too many such compounds haha.
DOC(dissolved organic compounds) are interchangeable with DOM(dissolved organic matter)


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## dw1305 (2 Dec 2019)

Hi all, 





jaypeecee said:


> But there are many other compounds relevant to aquarists under the heading of DOC, aren't there? In a quick search online, I found the following:
> 
> https://www.hindawi.com/journals/jchem/2016/1537370/


That is a useful reference.

DOC covers a whole range of substances and sources. If you collect a really nasty organic waster water (<"landfill leachate"> is the one I'm familiar with), it tends to be thick and black, with a high conductivity and an incredibly high BOD and TDS. It is really difficult <"to deal with">, because you have multiple issues.






In terms of aquariums the important bit of the paper is: 





> ........It is concluded that dissolved organic matter found in the water of the river from the site of minor human impact (Rucalhue) has a predominantly natural origin, with a high content of aromatic carbon, in contrast to dissolved organic matter found in the waters of the sites that have higher human impact (Laja and Concepción), characterized by a greater molecular size and higher organic carbon content.....


In <"tea stained "black water"> the tint is caused by relatively smaller organic molecules, these are often "aromatic compounds" (compounds that contain on or more <"benzene rings">).

Aromatic compounds are generally resistant to microbial degradation (<"Bacterial Degradation of Aromatic Compounds">), and can accumulate over time. I just asked our environmental chemist to give me a proper explanation, and she says you need to look at the "activation energies" of the compounds, and that gives you a measure of their <"inherent biodegradability">. Activation energies are the "low hanging fruits" analogy in <"What is organic waste">.

The researcher who has done a lot of work on humic, tannic and fulvic compounds is <"Christian Steinberg">, author of the standard reference <"Ecology of Humic Substances in Freshwaters: Determinants from Geochemistry to Ecological Niches.">

I don't have a copy unfortunately, it is £200 as a hard-back.

cheers Darrel


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## MJQMJQ (2 Dec 2019)

dw1305 said:


> Hi all, That is a useful reference.
> 
> DOC covers a whole range of substances and sources. If you collect a really nasty organic waster water (<"landfill leachate"> is the one I'm familiar with), it tends to be thick and black, with a high conductivity and an incredibly high BOD and TDS. It is really difficult <"to deal with">, because you have multiple issues.
> 
> ...



I have a suspicion that plants are able to absorb these substances that cause black water in aquarium because the colour disappears after time without any water change.Otherwise degradation by light.


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## dw1305 (2 Dec 2019)

Hi all, 





MJQMJQ said:


> I have a suspicion that plants are able to absorb these substances that cause black water in aquarium because the colour disappears after time without any water change.Otherwise degradation by light.


I think it is a combination of <"bacteria, plants and light">. It is back to the <"shades of grey"> scenario, with synergistic effects and complex food webs.

"Woody debris", like bog wood and structural leaf litter, degrades a lot more quickly in highly oxygenated, alkaline water and/or when you add nitrogen.

This is caused by a range of factors, and is partially because invertebrate shredders tend to be a lot more common in alkaline conditions, and they are <"initially fragmenting the leaves"> to allow easier microbial decomposition.

These processes can only occur if there is a high enough nitrogen to carbon ratio. We've recently been looking at a technique for estimating decomposition rates <"using cotton strips">.

Any-one who has kept shrimps will have seen that IAL leaves etc disappear  in their tanks, and even <"Alder "cones" degrade more quickly">.

The build-up of tannic, humic and fulvic substances, in "black water" rivers, is also a nutrient effect.  If you look at the <"conductivity values for the Rio Negro"> etc. there a very few ions of any description, and nitrogen (N), phosphorus (P),  potassium (K) etc. availability limits microbial (and micro-faunal)  break-down.  





> .......Low gradient rivers and streams run through sedimentary soils formed mainly by podsols subjected to seasonal flooding. The Rio Negro’s water is extremely poor in mineral content, with conductivity as low as 8 µS, and is extremely acidic, with pH’s ranging from 2.9 to 4.2..........


cheers Darrel


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## MJQMJQ (2 Dec 2019)

dw1305 said:


> Hi all, I think it is a combination of <"bacteria, plants and light">. It is back to the <"shades of grey"> scenario, with synergistic effects and complex food webs.
> 
> "Woody debris", like bog wood and structural leaf litter, degrades a lot more quickly in highly oxygenated, alkaline water and/or when you add nitrogen.
> 
> ...


I believe if its more alkaline then the bases would react with acids which are commonly released by organic substances hence they would turn into other substances.Its the same for land decomposition too ideal ratio C:N is about 20:1.Extreme acidity will make it hard for even bacteria to thrive and "preserves" the material.


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## MJQMJQ (2 Dec 2019)

jaypeecee said:


> Hi @MJQMJQ
> 
> I'm not sure whether it's polyurethane foam or some other polymer. Sorry to be pedantic but I would have thought carbon-impregnated foam would a*d*sorb oils as opposed to a*b*sorb them. But, perhaps I'm wrong. That aside, you are obviously thinking on the same lines as me. Are you suggesting that polyurethane foam would work on its own, i.e. without carbon impregnation?
> 
> JPC


Apparently so at least for oil spills in the ocean I think.Activated carbon would probably be more effective due to more pores that can trap oils.And since the research papers say absorb well I would think it is.Just do yr maintenance from time to time to prevent oils clogging everything up.


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## jaypeecee (2 Dec 2019)

Hi Folks,

A while ago, I discovered a paper by Dr Christian Steinberg. Here's some more bedtime reading for anyone who wants to delve further:

https://onlinelibrary.wiley.com/doi/full/10.1111/j.1365-2427.2006.01571.x

BTW, the link response time may be very slow but it's well worth the wait. The following snippet from this paper may well be of interest to those people who have cyanobacteria problems:

"For instance, the presence of HS suppresses cyanobacteria more than eukaryotic algae".

JPC


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## jaypeecee (2 Dec 2019)

dw1305 said:


> Any-one who has kept shrimps will have seen that IAL leaves etc disappear  in their tanks, and even <"Alder "cones" degrade more quickly">.



Couldn't resist picking out the above statement. It's amazing how the IAL/Catappa leaves perform their vanishing trick. I presume the leaves would also do this in a 'fish only' tank?

JPC


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## dw1305 (2 Dec 2019)

Hi all, 





jaypeecee said:


> It's amazing how the IAL/Catappa leaves perform their vanishing trick. I presume the leaves would also do this in a 'fish only' tank?


I think they will, but presumably more slowly. Some leaves are a lot more persistent than  IAL (_Terminalia catappa).  _@Lindy comments on leaf longevity in <"Leaves & Gravel">.

cheers Darrel


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## jaypeecee (2 Dec 2019)

dw1305 said:


> I think the issue is probably the lipid and wax component, it floats and will combine (both physically and chemically) with <"proteins, complex carbohydrates etc">.  This layer then supports bacteria, fungi etc.



Hi @dw1305 

If this lipid/wax mixture could be sucked off the surface _from above_, then that may remove this film. It may require something actually floating on the water surface. What about a carbon-impregnated sponge? Or, a fine structure foam/sponge (with good capillary action). At least, it shouldn't sink! If I can find any of these things in my many bits'n'pieces drawers/boxes, I'll give it a try. One other thought - if this lipid/wax mixture naturally floats, then the likes of _Purigen_ will never even 'see' it.

JPC


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## jaypeecee (6 Dec 2019)

jaypeecee said:


> I just need to get used to this piece of kit. It's further complicated by the fact that I had to make a 'livestock protector'. I am fully aware that some people have had problems with the Eheim skim350 as it can suck in small fish, shrimps, etc.



Hi Folks,

Please find attached my second attempt at a 'livestock protector'. It works pretty well. Why Eheim could not have included a suitable protector, I just don't know. The photograph shows the top of the floating section of the skim350, i.e. the inlet (obviously not in situ!).

JPC


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## jaypeecee (7 Dec 2019)

Hi Folks,

At the moment, this surface skimmer is doing an excellent job. No oily film whatsoever on the water surface - it looks like a mirror (from above and below the surface). Fingers crossed that I can keep it like this. And I can now maintain tighter control on dissolved CO2, which was the main driver for doing all this in the first place!

JPC


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## Zeus. (7 Dec 2019)

jaypeecee said:


> And I can now maintain tighter control on dissolved CO2,



and better O2 uptake at night  better O2 uptake better for inmates and canister filter media bacteria


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## jaypeecee (7 Dec 2019)

Zeus. said:


> and better O2 uptake at night  better O2 uptake better for inmates and canister filter media bacteria



So true. But I was getting seriously concerned about the dissolved CO2 level. Even the DC was moving towards yellow - but never got there.

JPC


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## Thumper (9 Dec 2019)

jaypeecee said:


> Why Eheim could not have included a suitable protector, I just don't know.


Green Aqua sells a 3D printed protector which replaces the top part. Works fien for me since a few weeks.


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## Oldguy (9 Dec 2019)

dw1305 said:


> Activation energies


I like to think of Activation Energy as the size of the brick behind the wheel of a car ( with no brakes) parked on the side of a hill. Spontaneous reactions just have Activation Energies lower than that provided by ambient temperatures, very tiny lego bricks.


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## jaypeecee (9 Dec 2019)

Thumper said:


> Green Aqua sells a 3D printed protector which replaces the top part. Works fien for me since a few weeks.



Hi @Thumper 

Thanks for mentioning that. Are you using the Green Aqua gizmo on the Eheim skim350?

JPC


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## Thumper (9 Dec 2019)

jaypeecee said:


> Are you using the Green Aqua gizmo on the Eheim skim350?


Yes. Without a sponge in the skimmer on half power. No problems.


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## jaypeecee (9 Dec 2019)

Thumper said:


> Yes. Without a sponge in the skimmer on half power. No problems.



Hi @Thumper 

Without a sponge!! So, what is removing the scum/film from the surface?

JPC


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## Thumper (9 Dec 2019)

jaypeecee said:


> So, what is removing the scum/film from the surface?


There is no scum  I just use the skimmer to reach CO2 levels faster and have more stable O2.


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## jaypeecee (9 Dec 2019)

Thumper said:


> There is no scum  I just use the skimmer to reach CO2 levels faster and have more stable O2.





JPC


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## Zeus. (9 Dec 2019)

jaypeecee said:


> JPC


----------



## jaypeecee (9 Dec 2019)

Hi @Zeus. 

Perhaps I should have explained. I can see why a suitably-positioned surface skimmer would help with CO2 distribution and O2 exchange. But the essence of the thread is all about removing surface film/scum caused by dissolved organics. Hence, the confusion.

BTW, do I detect a video there from Dennis Wong?

JPC


----------



## Zeus. (9 Dec 2019)

jaypeecee said:


> Hi @Zeus.
> 
> Perhaps I should have explained. I can see why a suitably-positioned surface skimmer would help with CO2 distribution and O2 exchange. But the essence of the thread is all about removing surface film/scum caused by dissolved organics. Hence, the confusion.
> 
> ...



Better O2 levels should 'I think' help reduce the DOC load of the tank as better O2 to the filter/substrate will result in the aerobic bacteria working better ! I'm sure @dw1305 Will confirm/dismiss this 

Yep D Wong


----------



## Thumper (10 Dec 2019)

jaypeecee said:


> But the essence of the thread is all about removing surface film/scum caused by dissolved organics.


Yes, but in a healthy tank there is no surface scum, because it can get removed by bacteria before it starts to appear.


----------



## dw1305 (10 Dec 2019)

Hi all,





Zeus. said:


> help reduce the DOC load of the tank as better O2 to the filter/substrate will result in the aerobic bacteria working better !..Will confirm/dismiss this


Yes, I think so. It is the <"activated sludge scenario">, just with higher quality water initially.

cheers Darrel


----------



## jaypeecee (10 Dec 2019)

Thumper said:


> Yes, but in a healthy tank there is no surface scum, because it can get removed by bacteria before it starts to appear.



Hi @Thumper 

I guess we need to start by looking at what you mean by "a healthy tank". Lots of people, including myself, would consider that we have 'healthy' tanks. But we may still get a surface scum or oily film because these naturally develop in an enclosed system and in natural waters. Please take a look at the following:

https://www.ukaps.org/forum/threads/does-ferrous-gluconate-cause-a-water-surface-film.58550/

In my tanks, I have often measured the oxygen level and they consistently measure 8ppm - this would suggest that oxygenation is not an issue. So, if surface scum is being "removed by bacteria before it starts to appear", does that mean that I don't have the 'right' bacteria in my tank? If that's the case, I want some!

JPC


----------



## Thumper (10 Dec 2019)

jaypeecee said:


> In my tanks, I have often measured the oxygen level and they consistently measure 8ppm - this would suggest that oxygenation is not an issue. So, if surface scum is being "removed by bacteria before it starts to appear", does that mean that I don't have the 'right' bacteria in my tank? If that's the case, I want some!


Thats exactly what i'm talking about.
A healty tank has (IMO) the right and enough bacterias. How you get them? Stable and smooth first 2-3 month with low - medium light, so that there wont be huge algae or nutritien imbalances (BGA, green glass/rocks).
The next thing i have a huge focus on is filter maintenance. I gently wash off debris from my filter media every 4 weeks. This results in low DOC and enough O2 throughout the filter. 

As for bacterias, in our german forum is a huge discussion about the microflora. Right now we have no results, as we cant prove anything _but _the best results are in those tanks where we have low DOC, a smooth first phase and stable water parameters.
A friend is currently testing 2 things: 1) compost brew every other day. 2) Mykorrhiza fungi. I can keep you posted.


----------



## jaypeecee (10 Dec 2019)

Thumper said:


> As for bacterias, in our german forum is a huge discussion about the microflora. Right now we have no results, as we cant prove anything _but _the best results are in those tanks where we have low DOC, a smooth first phase and stable water parameters. A friend is currently testing 2 things: 1) compost brew every other day. 2) Mykorrhiza fungi. I can keep you posted.



Hi @Thumper 

Thank you for your reply. Of particular interest is your German forum microflora discussion. Unfortunately, I am not conversant with the German language so your translation will be very welcome. I assume that your microflora discussion also includes Archaea. Please explain what is meant by "compost brew every other day". Others may know what this means but, for my benefit, what is compost brew? I do have limited knowledge of mycorrhizal fungus as I use it in my garden. Finally, how do you measure/monitor DOC?

Please keep us posted.

JPC


----------



## Thumper (11 Dec 2019)

jaypeecee said:


> Please explain what is meant by "compost brew every other day". Others may know what this means but, for my benefit, what is compost brew?


Take 1 spoon of healthy compost earth and dissolve it in 500ml water. if you want, you can filter it through a coffee filter. This water should now be enriched with many many bacterias and bacteria food.



jaypeecee said:


> I do have limited knowledge of mycorrhizal fungus as I use it in my garden.


We're pretty unexperienced too. Time will show if it works.



jaypeecee said:


> Finally, how do you measure/monitor DOC?


Well, the only way to measure it is with a fine (but not to fine) membrane. We don't measure it, but tests showed, that with stable O2 levels mulm will eventually be a stable amount.
In many tanks without any filtration and just a circulation pump, sand substrate, many plants and a stable O2 level there is also a stable mulm amount - not getting more/less.


----------



## dw1305 (11 Dec 2019)

Hi all, 





Thumper said:


> Take 1 spoon of healthy compost earth and dissolve it in 500ml water. if you want, you can filter it through a coffee filter. This water should now be enriched with many many bacterias and bacteria food.


I'm interested in how this works. I can see a rationale for it. My suspicion would be that it is going to offer some of the same advantages as <"structural leaf litter">.

These are the processes that <"Stephan Tanner"> talks about in <"Aquarium Biofiltration">. 





Thumper said:


> As for bacterias, in our german forum is a huge discussion about the microflora.


I think you are probably much more likely to get informed debate on German fish keeping forums. It is back to the <"shades of grey"> world, in the English speaking world I don't think we are very good at visualising complex interactions, we like "linear" and "black and white" answers and I think we are much more likely to resort to a chemical or technological "solutions". 





Thumper said:


> In many tanks without any filtration and just a circulation pump, sand substrate, many plants and a stable O2 level there is also a stable mulm amount - not getting more/less.


I also think an <"amount of mulm"> may offer advantages.





Thumper said:


> but tests showed, that with stable O2 levels mulm will eventually be a stable amount.


This is as  the result of the <"complete oxidation process">.

cheers Darrel


----------



## jaypeecee (11 Dec 2019)

Thumper said:


> Well, the only way to measure it is with a fine (but not to fine) membrane. We don't measure it, but tests showed, that with stable O2 levels mulm will eventually be a stable amount. In many tanks without any filtration and just a circulation pump, sand substrate, many plants and a stable O2 level there is also a stable mulm amount - not getting more/less.



Hi @Thumper 

Referring to your first sentence above, I guess that would be a membrane allowing substances from 0.22 micrometres to 0.7 micrometres to pass through it?

Your last sentence is a very significant observation, isn't it? That's quite a discovery. Of course, manufacturers of canister filters, for example, will probably challenge this. I don't suppose it's what they'd want to hear.

JPC


----------



## Thumper (11 Dec 2019)

jaypeecee said:


> Your last sentence is a very significant observation, isn't it?


Its widely accepted in germany since a decade for hobbyists. For reference check this post. He only uses ceramic rings and observes that the mulm-spots in the filter move from time to time and also sometimes fill find their way back into the tank. Occassionally he'll vacuum his gravel, as he has fish in the tank. But for tank without any stock there wont be more/less mulm - everything gets recycled.

Sure, manufactureres want to sell everything. I mean, Seachem sells Matrix for $$$$ while its just pumice stone - and even ADA Bio Rio (which is also pumice) is cheaper than Matrix. But if i go to your local DIY store you get 20L pumice stone 8-16mm for ~10-15€. Seachem Matrix 20L is 199€.

Back to the topic: I only use a filled filter (with pumice) to maintain enough bacteria. As i remove the mulm in the filter every month i get my stable portion of mulm in my tank. And btw, my filter medium is never really dirty. More like dusty.


----------



## Zeus. (11 Dec 2019)

Thumper said:


> Sure, manufactureres want to sell everything. I mean, Seachem sells Matrix for $$$$ while its just pumice stone - and even ADA Bio Rio (which is also pumice) is cheaper than Matrix. But if i go to your local DIY store you get 20L pumice stone 8-16mm for ~10-15€. Seachem Matrix 20L is 199€.



Cut though the sales BS and get the same product for peanuts  We are all fans of getting passed the BS


----------



## dw1305 (11 Dec 2019)

Hi all, 





jaypeecee said:


> I guess that would be a membrane allowing substances from 0.22 micrometres to 0.7 micrometres to pass through it?


Yes, its just a <"gas permeable membrane">.I think the pore size is a bit smaller, but I can't remember exactly how small.

You <"calibrate the DO meter"> in 100% water vapour saturated air and the meter has  automatic temperature and atmospheric pressure compensation.

Better meters offer you a choice of water-saturated air or a Winkler titration calibration and also have a conductivity meter to allow manual compensation for increased conductivity. They are <"quite easy bits of kit to use">. 

The issue is just the cost of the probe/meter. You can also get <"optical meters">. They are really good, but a bit more expensive again.





Thumper said:


> I mean, Seachem sells Matrix for $$$$ while its just pumice stone - and even ADA Bio Rio (which is also pumice) is cheaper than Matrix. But if i go to your local DIY store you get 20L pumice stone 8-16mm for ~10-15€.





Zeus. said:


> Cut though the sales BS and get the same product for peanuts


That <"is the truth">. 

We have a few pumice threads. These are <"Filter media">, <"...Renew"> & <"Hobby laterite">.

cheers Darrel


----------



## Oldguy (12 Dec 2019)

Do healthy plants leak organics? 

Just an observation, Otos et al are often very busy on plant leaves that are strong, healthy and have no obvious algae. Are they grazing on films formed on these leaves by lipids and other complexes and does the removal of such films helps prevent algae colonising such surfaces. Or perhaps colonising micro flora/fauna feed on these films and their presence becomes a stepping stone for algae and their removal makes it harder for algae to become established. A series of micro  successions leading to algae as the climax coloniser.

Having finally grasped the nettle and removed several large Anubias barteri var barteri and replanting with stem plants my Otos and similar have become very interested in the growing leaves, even the corys have been busy 'dusting' these leaves. Previously the corys were only interested in the undersides of cryp leaves for spawning sites. Anubias have thick glossy leaves and would perhaps be less leaky and of less interest to my little guys.

Just some thoughts on a wet rainy day.


----------



## jaypeecee (12 Dec 2019)

Oldguy said:


> Just an observation, Otos et al are often very busy on plant leaves that are strong, healthy and have no obvious algae.



Hi @Oldguy 

This is something I've noticed many times and been intrigued by it. Yesterday, I was chatting with an ichthyologist who confirmed what I had long suspected, which is that Otos (and others) feed on something known as periphyton. Please take a look at:

https://en.wikipedia.org/wiki/Periphyton

We, as aquarists, would probably refer to this as biofilm. But, according to Wikipedia, biofilms can take many forms - including dental plaque! If interested, please see below:

https://en.wikipedia.org/wiki/Biofilm

And it's now an even wetter, rainy day. 

JPC


----------



## Oldguy (12 Dec 2019)

jaypeecee said:


> aquarists, would probably refer to this as biofilm



Good evening @jaypeecee, Thank you for your links, most interesting. Nothing in life is good or bad. I rely of biofilm [hopefully the good guys] in my wet/dry trickle filter which I modeled on a sewerage works treatment plant as a important part of my tank set up.

Complex films of chemicals, bacteria, protozoa, rotifers and fungi are intriguing. As a young lad I fell in love with rotifers and spent many hours looking into bird-bath films with a pocket microscope, much to the chagrin of some of my teachers and the wry support of my headteacher who could not make me out but gave much support.

Keeping fish in a planted tank brings all branches of science together with a wealth of practical observation and application. We learn new things every day, long may it continue.


----------



## dw1305 (16 Dec 2019)

Hi all, 





jaypeecee said:


> Yesterday, I was chatting with an ichthyologist who confirmed what I had long suspected, which is that Otos (and others) feed on something known as periphyton.


I'm a <"periphyton fan"> as well.  

There is quite a lot of discussion of <"periphyton,  aufwuchs"> etc on PlanetCatfish, where a lot of the Loricariid catfish are <"specialised aufwuchs"> feeders.

cheers Darrel


----------



## jon32 (4 Feb 2020)

Hi, Interesting thread. I can rule out fish food as my 60X30X18 high tech tank always has surface film. The tank only has a few cherry shrimp and is heavily planted. I don't feed the shrimp I just leave alone to graze on the biofilm.


----------



## jaypeecee (9 Feb 2020)

Hi Folks,

I very recently stumbled across this post:

https://www.ukaps.org/forum/threads...d-about-bacteria-in-filter.28795/#post-299821

Note the comment that "plants produce a LOT of waste, especially if the tank is enriched with CO2 via gas or liquid". So, does this not support the idea of continuously removing DOCs using suitable filtration media such as Seachem _Purigen_? Is this what other UKAPS members do?

JPC


----------



## zozo (9 Feb 2020)

Plants do release / respirate a lot of organics, think of smell for example  to attract pollinators or to repel predators. 

Think of the good-smelling essential oils, people extract from all kinds of plants and put it concentrated in a bottle.

It's this stuff that is a building block from the oily biofilm scum layer we sometimes see on the water surface in our aquariums.


----------



## dw1305 (9 Feb 2020)

Hi all,





jaypeecee said:


> Note the comment that "plants produce a LOT of waste, especially if the tank is enriched with CO2 via gas or liquid"


That is part of the reason for the big water change in EI and why people run surface skimmers, overflows etc. Marine reef aquarists use <"protein skimmers">, but these don't really work in freshwater.





jaypeecee said:


> So, does this not support the idea of continuously removing DOCs using suitable filtration media such as Seachem _Purigen_?


 In terms of the "Purigen" it is back to the <"size of the particles"> it removes. In terms of large non-dissolved particles and fine mechanical filtration, you just need to ensure that you change the filter media over really frequently to avoid clogging. 

The answer to a lot of these questions is really to do with oxygen, natural systems low in DOC tend to be <"nutrient poor, highly oxygenated and with alkaline water">.  As you move away from these scenarios (or look at the wider picture) then the situation becomes <"more complicated">.   

In terms of DOC generally, it is an entirely natural component of all aquatic systems, just in differing amounts. Is there any advantage to its complete removal, I'm pretty sure that answer is "no", and that if you could get water entirely devoid of DOC it would impinge on fish health. There is quite a lot of <"scientific research in this area">, although @jaypeecee may not like the <"shades of grey"> aspect to it.

Personally I think that the <"BOD concept"> is more useful, which is why you <"can have tanks full of structural leaf litter and dead wood">, but with very high water quality. 

cheers Darrel


----------



## Witcher (9 Feb 2020)

dw1305 said:


> you <"can have tanks full of structural leaf litter and dead wood">, but with very high water quality.



Not to mention that dead leaves/wood is a source of cellulose which is absolutely necessary for many sucker fish (Ottos etc.). Can't find sources now but it's related with the health of their digestive system.


----------



## jaypeecee (9 Feb 2020)

dw1305 said:


> ...although @jaypeecee may not like the <"shades of grey"> aspect to it.



Hi Darrel...you've got me sussed. 

JPC


----------



## jaypeecee (9 Feb 2020)

dw1305 said:


> In terms of the "Purigen" it is back to the <"size of the particles"> it removes.



Hi Darrel,

My concern is not about particulate matter - that's easy to remove with mechanical filtration. Let's go back to the start - surface film. As surface film appears to be caused by dissolved organics, then how do we remove these organics? Isn't this what products like _Purigen_ are supposed to do? And, if the likes of _Purigen_ are effective, why do we not hear mention of this on UKAPS? Do you know of anyone that uses _Purigen_ or similar materials?

Edit: I do realize that some organics, e.g. humic substances, are beneficial. So, perhaps the only solution to the surface film problem is the surface skimmer. Although I have an Eheim _skim350_, I have found it difficult to get it to work reliably and it's another unwelcome piece of kit in an 125l tank.

JPC


----------



## jaypeecee (10 Jun 2020)

Hi Folks,

I was reading Diana Walstad's book* today and she was discussing allelopathy. She says "Aquatic plants probably release large amounts of allelochemicals, for they are leaky when they're alive...". This supports what @dw1305 has previously mentioned. That made me think. Is this why we sometimes see BBA growing along the edges of leaves? Is it from here that plants are leaking nutrients/organic compounds into the water column?

* _Ecology of the Planted Aquarium_

JPC


----------



## jaypeecee (29 Jul 2020)

Hi Folks,

Although the question raised by my original post in this thread has been answered, may I return to the question that I put forward in post #70? My interest in organics continues and I wonder if it gets the attention that it possibly deserves? It was surface film on the water that prompted me to ask the original question. But, I now wonder what part organics play in promoting algae and cyanobacteria (aka BGA), just as one/two examples. In using the term 'organics', I mean all of the following:

DOC (Dissolved Organic Carbon)
DOM (Dissolved Organic Matter)
Particulate Organic Carbon
Organic Compounds
etc!

Referencing the same source as in post #71, it seems that many organic compounds released by aquatic plants decompose very slowly - we're talking weeks, months and longer. Frequent water changes are obviously one way of controlling organics. Another is the use of activated carbon or products such as Seachem's Purigen.

Any and all feedback would be appreciated.

JPC


----------



## dw1305 (29 Jul 2020)

Hi all, 





jaypeecee said:


> it seems that many organic compounds released by aquatic plants decompose very slowly


The rate of decomposition is directly related to the energy balance between energy expended in decomposition and the energy harvested.  Carbon : nitrogen ratio is also important.

Sugars and proteins are easy to decompose, because they can be dismembered very easily. Lignin  and humic compounds are slow to degrade because the energy expended in their decomposition is almost equal to the energy harvested. If the energy expended in decomposition exceeds the energy harvested then a substance isn't biodegradable. 

That is  why you can add potato starch to a plastic polymer, it tips the balance to "biodegradable".

cheers Darrel


----------



## jaypeecee (29 Jul 2020)

Hi @dw1305 

Thanks for your reply.

So, my question is - how do we mitigate against organics building up? I realize that you're not in favour of testing water parameters but do you know how we can quantify and control organics building up? What about activated carbon and the likes of _Purigen_?

JPC


----------



## Wookii (30 Jul 2020)

jaypeecee said:


> Hi @dw1305
> 
> Thanks for your reply.
> 
> So, my question is - how do we mitigate against organics building up? I realize that you're not in favour of testing water parameters but do you know how we can quantify and control organics building up?



Dissolved organics are most easily removed by maintenance. Water changes are the most effective method to remove them, and why we do such large and regular water changes. Also cleaning the filter more regularly, not overfeeding fish, removing dying and loose leaves, siphoning any detritus build up etc will all help lower organics, but water changes are perhaps the most effective.

Dissolved oxygen levels also obviously help break down organics, so maximising DO should also help break down organics more effectively. Surface skimming is also effective as you have already mentioned - since it removes the organic film on the water surface, removing those organics, but also increasing gas exchange (and presumably DO levels) (PS - if you want a much more effective and easier to use skimmer than the Eheim 350, try the APS SKIM-2).

Darrel will I'm sure be able to give you more detail, but monitoring TDS is the simplest way to track gradually increasing organics - though if you use tap water for water changes, you need to keep an eye on tap water TDS also as mine varies quite a lot throughout the year.



jaypeecee said:


> What about activated carbon and the likes of _Purigen_?
> 
> JPC



Activated carbon is a bit more indiscriminate and will absorb a wider range of substances. Purigen is marketed as absorbing mainly dissolved organics. I use it in my filters, as I imagine do the majority of high tech tank owners on this forum, and it appears to be an effective addition as far as I am able to observe.


----------



## dw1305 (30 Jul 2020)

Hi all, 





jaypeecee said:


> So, my question is - how do we mitigate against organics building up? I realize that you're not in favour of testing water parameters but do you know how we can quantify and control organics building up?


I have measured TDS, in more polluted water, by "evaporation to dryness", it is much <"more difficult in cleaner water">, because you have to evaporate a very large volume of water to get a measurable amount of TDS.





Wookii said:


> Water changes are the most effective method to remove them, and why we do such large and regular water changes.


Pretty <"much exactly what"> @Wookii  says,  water changes and high DO are my default as well.  It is back to the <"BOD concept">, as the organic load goes up you need to add more oxygen to process it, and more water changes (and plants) to dilute the remaining water. 

<"Humic substances are persistent"> because they have  a low BOD.





jaypeecee said:


> What about activated carbon and the likes of _Purigen_?


I like <"some tint in the water">, so charcoal or  Purigen doesn't make any sense for me.

If I kept <"Lake Tanganyika fish"> I would  want clear water, but for soft water fish I think some humic compounds offer an advantage. I don't measure the tint, I just adjust it by eye.

In my earliest incarnation as a fish-keeper <"I had a lot of water issues"> , some of which manifested themselves in tinted water,  but water changes put a stop to that.

cheers Darrel


----------



## jaypeecee (30 Jul 2020)

Hi @Wookii


Wookii said:


> ...monitoring TDS is the simplest way to track gradually increasing organics...



If you have the gear to actually measure total dissolved solids, then that would be a possibility. But, if you rely on a 'TDS' meter, you'll be in for a surprise. These meters measure electrical conductivity and convert this to a TDS reading. The problem is that many organic compounds will not register on a TDS meter as they are not electrically conductive. Try it for yourself. I just took 250ml of rain water (from a rain butt). Its conductivity was 93 microS/cm. I then added 1/8tsp (0.63ml) of granulated white sugar and stirred very well. The resulting conductivity was 93 microS/cm. Zero change. Try it for yourself sometime. Common salt, on the other hand, is comprised of sodium and chloride ions in solution and _is_ detectable by a TDS meter.

JPC


----------



## Wookii (30 Jul 2020)

jaypeecee said:


> Hi @Wookii
> 
> 
> If you have the gear to actually measure total dissolved solids, then that would be a possibility. But, if you rely on a 'TDS' meter, you'll be in for a surprise. These meters measure electrical conductivity and convert this to a TDS reading. The problem is that many organic compounds will not register on a TDS meter as they are not electrically conductive. Try it for yourself. I just took 250ml of rain water (from a rain butt). Its conductivity was 93 microS/cm. I then added 1/8tsp (0.63ml) of granulated white sugar and stirred very well. The resulting conductivity was 93 microS/cm. Zero change. Try it for yourself sometime. Common salt, for example, is comprised of sodium and chloride ions in solution and _is_ detectable by a TDS meter.
> ...



You have to remember you're running a hobby aquarium not getting ready to draft a scientific white paper. Monitoring an aquarium, is about general relative values and a holistic overview, so seeing a gradual increase in TDS will give you an indication that you may have increasing organics.  You're unlikely to get a pure increase in non-conductive organics in an aquarium, without an increase in conductive organics also, so you'll be able to measure any increase reliably enough to know if you need to increase water changes and maintenance to keep it stable and stop it rising continually. If your increased water change schedule halts the steady increase in TDS, then you now your intervention was the correct one.


----------



## jaypeecee (30 Jul 2020)

Hi @Wookii 

I had hoped that we could discuss this in a friendly manner. But, I sense that it's not going that way. That's a real shame.

JPC


----------



## Wookii (30 Jul 2020)

jaypeecee said:


> Hi @Wookii
> 
> I had hoped that we could discuss this in a friendly manner. But, I sense that it's not going that way. That's a real shame.
> 
> JPC



Sorry if you misunderstood my post, nothing was intended as unfriendly in the slightest way?


----------



## dw1305 (30 Jul 2020)

Hi all, 





Wookii said:


> Monitoring an aquarium, is about general relative values and a holistic overview, so seeing a gradual increase in TDS will give you an indication that you may have increasing organics. You're unlikely to get a pure increase in non-conductive organics in an aquarium, without an increase in conductive organics also....If your increased water change schedule halts the steady increase in TDS, then you now your intervention was the correct one.


That would be the view I've taken, you can use the BOD concept, conductivity and plant health as a proxy for nutrient status and water quality.

It isn't perfect, but it gives you a framework to work with and doesn't require a lot of expensive equipment  or a large input of time. 

cheers Darrel


----------



## jaypeecee (30 Jul 2020)

Hi @Wookii


Wookii said:


> Sorry if you misunderstood my post, nothing was intended as unfriendly in the slightest way?



OK, I'll pass on your first sentence in post #78 and start again.


Wookii said:


> ...so seeing a gradual increase in TDS will give you an indication that you may have increasing organics.



I don't understand why a gradual increase in electronically-measured 'TDS' has any bearing on organics. I do know that cellulose, for example, is electrically non-conductive. I would need to check the rest. According to Diana Walstad:

"Decomposition of plant residues after one year were found to be 99% for sugars, 90% for hemicellulose, 75% for cellulose, 50% for lignins, 25% for waxes and only 10% for phenolic compounds".

To which we may then add liquid carbon (e.g. glutaraldehyde), chelators, etc. Although this thread set out to target healthy plants, I am guessing that what we are discussing here is equally applicable to decaying plants. It has often been said (by @dw1305) that plants are leaky structures. Indeed, he may have said this earlier in this very thread.

JPC


----------



## dw1305 (30 Jul 2020)

Hi all, 





jaypeecee said:


> I don't understand why a gradual increase in electronically-measured 'TDS' has any bearing on organics.


It doesn't directly, but polluted (high BOD) water usually has both higher conductivity and ppm TDS (measured by evaporation). 

If you add nutrients at least some of the products of their decomposition will be ions, so if you add a protein, it will eventually end up as nitrate (NO3-), via the breakdown of amino acids and the nitrification of ammonia.

You can have <"high conductivity, low TDS water"> like a chalk stream, and low conductivity, high TDS water like a tropical black-water stream, but they both have a low BOD. That is why you need a <"datum value">, for your tap or rain water, before conductivity becomes a useful measurement.

cheers Darrel


----------



## jaypeecee (31 Jul 2020)

Hi Folks,

I was wondering if it would be possible to try some of the procedures described in the following (they're probably familiar to @dw1305 ):

https://water.custhelp.com/app/answ...ons_-correlation-between-kmno4,-cod,-bod,-doc

Or, what about this:

1 Take sample of aquarium water
2 Insert ORP/Redox probe and note reading when settled (10 minutes or so)
3 Every 10 minutes or so, add a calculated volume of KMnO4* solution *or* H2O2** solution monitoring ORP for any changes (increase) with each addition. In the case of KMnO4, there may also be a colour change from purple to brown to purple.
4 Note the volume of KMnO4 or H2O2 added when the point is reached at which ORP starts to increase (or colour change with KMnO4)

My thinking is that, when ORP starts to increase, the oxidation/reduction balance will have been reached. And, from this, it may be possible to calculate DOM*** concentration. In principle, can anyone see any errors in my reasoning?

*  potassium permanganate
** hydrogen peroxide
*** dissolved organic matter

JPC


----------



## dw1305 (31 Jul 2020)

Hi all, 





jaypeecee said:


> 1 Take sample of aquarium water
> 2 Insert ORP/Redox probe and note reading when settled (10 minutes or so)
> 3 Every 10 minutes or so, add a calculated volume of KMnO4* solution *or* H2O2** solution monitoring ORP for any changes (increase) with each addition. In the case of KMnO4, there may also be a colour change from purple to brown to purple.
> 4 Note the volume of KMnO4 or H2O2 added when the point is reached at which ORP starts to increase (or colour change with KMnO4)


Yes it is the <"COD method">. 

<"Potassium dichromate"> is a better oxidising agent than hydrogen peroxide or potassium permanganate, but it is still of very limited value to us, it really only gives you a "quick and dirty" estimation for very polluted water.

cheers Darrel


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## jaypeecee (31 Jul 2020)

Hi @dw1305 


dw1305 said:


> ...it really only gives you a "quick and dirty" estimation for very polluted water.



Thanks, Darrel. I appreciate the feedback. What is the reason for this method not being sufficiently sensitive to measure organics in freshwater tanks?

There is a company in Czechoslovakia that produces a freshwater organics aquarium test kit. I'll check it out. I tried the Salifert Organics test kit some time ago but it was a big disappointment. I'll also try to collect my thoughts on why I think this topic is worth pursuing. At the moment, I realize that I'm a lone voice on this.

I've also noticed that the term 'DOM' may be the better one to use as it includes dissolved organic phosphorus, for example. And, fish pheromones.

JPC


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## sparkyweasel (31 Jul 2020)

jaypeecee said:


> I'll also try to collect my thoughts on why I think this topic is worth pursuing.


For what it's worth: I'm finding it interesting to follow your thoughts and research on this. I just don't have much to contribute, more like trying to keeep up.


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## dw1305 (1 Aug 2020)

Hi all, 





jaypeecee said:


> What is the reason for this method not being sufficiently sensitive to measure organics in freshwater tanks?


 It is because COD is a pretty broad brush. The COD is the oxygen demand from all chemically oxidisable organic carbon (C). The oxidising agent (potassium dichromate etc), used in the assessment of COD, burns out all of the organic C, including the component not easily broken down by microbial action. Because of this it tends to underestimate the <"BOD demand"> of ammonia etc. 

If you think of the tannin tinted water, it might have low BOD, <"a high biotic index"> and moderate COD. A waste stream with lots of ammonia, but very few particulates, might have a very high BOD, very low Biotic Index and a relatively low COD

Five day BOD is a much more sensitive test, but still less good than a <"Biotic Index">.  <"A sonde using tryptophan fluorescence"> gives a better estimation of BOD than COD, but you would still use it with a Biotic Index.  The Biotic Index is always going to give you the best estimation of long term water quality in natural waters. 

The current Biotic Index for the UK is the <"Whalley, Hawkes, Paisley & Trigg revision to BMWP">.

cheers Darrel


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## jaypeecee (1 Aug 2020)

Hi @dw1305


dw1305 said:


> Five day BOD is a much more sensitive test...



Thanks, Darrel. I once did a 5-day BOD on a tank. So, that's worth trying, yes? Thanks for the link to the Biotic Index.

JPC


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## jaypeecee (1 Aug 2020)

Hi @sparkyweasel 


sparkyweasel said:


> For what it's worth: I'm finding it interesting to follow your thoughts and research on this. I just don't have much to contribute, more like trying to keeep up.



I really appreciate your feedback - thank you!

JPC


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## dw1305 (2 Aug 2020)

Hi all, 





jaypeecee said:


> I once did a 5-day BOD on a tank. So, that's worth trying, yes?


Yes, we used to do a lot of these, but you really need <"dedicated lab space">. 





> <"Standard Methods 5210B">. A sample is first analyzed and conditioned to ensure favourable growth conditions for bacteria, which may include adjustment for pH, neutralization of residual chlorine, and/or reduction of DO in supersaturated samples. The sample is then diluted and the appropriate amount of seed bacteria added. The initial dissolved oxygen content is recorded and the sample is then incubated for 5 days at 20°C. After the 5 day period, the sample is removed from the incubator and the final dissolved oxygen reading is taken. BOD is calculated from the DO depletion and volume of sample used following the formula below:
> 
> BOD5 = BOD mg/L = [(IDO -DO5) – seed correction] x dilution factor


cheers Darrel


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## jaypeecee (2 Aug 2020)

Hi @dw1305 & Everyone,

Needless to say, the above procedure isn't quite the one I followed! Remember the books of years gone by when the "Beginners' Guide To..." series were popular? Well, I reckon I must have followed the "Beginners' Guide to Biochemical Oxygen Demand testing"!  If I remember rightly, I took a 1 litre sample of aquarium water and measured the DO* content. Then, sealed the 1 litre sample container and put it in a dark place for five days. When time was up, I then re-measured the DO* content. Going by memory, not a ha'porth of difference!

What do you know about Permanganate Value? Is this appropriate for measuring DOM**? Isn't it used by pondkeepers?

For the benefit of anyone who is not familiar with acronyms I've used:

*DO = Dissolved Oxygen
** DOM = Dissolved Organic Matter

JPC


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## dw1305 (2 Aug 2020)

Hi all, 





jaypeecee said:


> What do you know about Permanganate Value?Is this appropriate for measuring DOM**?


It is a less effective than potassium dichromate.  Potassium permanganate doesn't as effectively oxidize all the organic compounds in water, limiting its value for determining COD.  The main issue with all the COD methods is that they don't oxidise any ammonia into nitrate, so nitrification is not included in the standard COD test, but they do oxidise tannic and humic compounds, which don't really contribute to the BOD . 





jaypeecee said:


> Isn't it used by pondkeepers?


I think potassium permanganate is still used as a dip for parasites. I was going to say I really  hope not as a water treatment, but it probably is, mainly because you could sell permanganate, COD test kit and"sludge busting" bomb.





jaypeecee said:


> Needless to say, the above procedure isn't quite the one I followed!


It is really why you need a lab set up for it. You need to culture the microbes, as well as having access to the growth cabinets and reagents. I used to assume that the values we got were fairly accurate, but we were dealing with fairly polluted water. 

In cleaner water (and hopefully that includes in every-ones aquarium water) then it still doesn't give you anything like fine enough scale resolution. 

cheers Darrel


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## jaypeecee (2 Aug 2020)

Hi @dw1305 

It's back to the drawing board for me!

Thanks for your replies.

JPC


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## dw1305 (9 Sep 2020)

Hi all,
An interesting paper has come my way. It looks at the interaction between dissolved organic carbon (DOC), nitrification and the microbial assemblage. The paper is open source, and should be available to every-one:

Navada, S., Knutsen, M.F., Bakke, I. _et al._  (2020) <"Nitrifying biofilms deprived of organic carbon show higher functional resilience to increases in carbon supply">. _Sci Rep_ *10.*


> ........ the organic carbon to ammonia nitrogen (C/N) supply ratio can influence resource competition between heterotrophic and nitrifying bacteria for oxygen and space. We investigated the impact of acute and chronic changes in carbon supply on inter-guild competition in two moving bed biofilm reactors (MBBR), operated with (R1) and without (R0) external organic carbon supply. The microbial and nitrifying community composition of the reactors differed significantly. Interestingly, acute increases in the dissolved organic carbon inhibited nitrification in R1 ten times more than in R0.
> 
> *A sustained increase in the carbon supply decreased nitrification efficiency and increased denitrification activity to a greater extent in R1, and also increased the proportion of potential denitrifiers in both bioreactors...... Specifically, efficient removal of organic matter before the nitrification unit can improve the robustness of the bioreactor to varying influent quality*.
> 
> Thus, maintaining a low C/N ratio is important in nitrifying biofilters when acute carbon stress is expected or when anoxic activity (e.g. denitrification or H2S production) is undesirable, such as in recirculating aquaculture systems (RAS).


Which can be digested as:

"_a lot of of organic matter in your filter reduces nitrification, but increases denitrification_".

Which partially explains why not using your filter as a syphon, not letting it get too gungy and having a pre-filter, helps with nitrification. Nitrate (NO3-) can always be mopped up by plants and water changes.

cheers Darrel


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## jaypeecee (16 May 2021)

dw1305 said:


> An interesting paper has come my way. It looks at the interaction between dissolved organic carbon (DOC), nitrification and the microbial assemblage. The paper is open source, and should be available to every-one:
> 
> Navada, S., Knutsen, M.F., Bakke, I. _et al._ (2020) <"Nitrifying biofilms deprived of organic carbon show higher functional resilience to increases in carbon supply">. _Sci Rep_ *10.* Which can be digested as:
> 
> "_a lot of of organic matter in your filter reduces nitrification, but increases denitrification_".


Hi Darrel (@dw1305)

I have just (re)discovered the above paper that you mentioned. What an excellent find! Thanks.

JPC


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## jaypeecee (17 May 2021)

Hi Folks,

Having now done a lot of ORP* measurements with varying water conditions, I am very much of the view that there is a correlation between dissolved organics and ORP. I think this is because dissolved organics are broken down by heterotrophic bacteria. And, this process consumes oxygen. Since ORP is the oxidation-reduction potential, a drop in oxygen concentration will be detected by an ORP meter. That's my hypothesis. If I'm correct, then this makes an ORP meter a useful dissolved organics/dissolved oxygen indicator.

*also referred to as 'redox potential'

JPC


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## Wookii (17 May 2021)

jaypeecee said:


> Hi Folks,
> 
> Having now done a lot of ORP* measurements with varying water conditions, I am very much of the view that there is a correlation between dissolved organics and ORP. I think this is because dissolved organics are broken down by heterotrophic bacteria. And, this process consumes oxygen. Since ORP is the oxidation-reduction potential, a drop in oxygen concentration will be detected by an ORP meter. That's my hypothesis. If I'm correct, then this makes an ORP meter a useful dissolved organics/dissolved oxygen indicator.
> 
> ...



Genuine question; What about in a CO2 injected tank where full DO saturation is achieved on a daily basis? Would to ORP measurement still indicate a change in dissolved organics?


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## jaypeecee (17 May 2021)

Hi @Wookii 



Wookii said:


> What about in a CO2 injected tank where full DO saturation is achieved on a daily basis? Would to ORP measurement still indicate a change in dissolved organics?



Very good question. If you have the means to accurately measure 'full DO saturation' in your tank water column, it would be interesting to also measure ORP at the same time. Unfortunately, I am unable to measure dissolved oxygen other than to use the JBL dissolved oxygen test kit. The colour patch variation from 6 to 10 ppm in this kit is minimal. I guess you could use the presence of plant pearling as an indicator of DO saturation.

JPC


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## Wookii (18 May 2021)

jaypeecee said:


> Hi @Wookii
> 
> 
> 
> ...



I don’t, no, sadly. I’ve always fancied having a play with a DO meter, but they are a bit too cost prohibitive for the amount I would end up using one.

As you say though, I am basing it on the fact I get significant pearling, even in higher flow areas where static areas of O2 saturated water immediately around the leaves are less likely.

It just made me think that kind of DO level would likely exist regardless of the level of dissolved organics (up to a sensible point ofcourse).


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