# So what is organic wastes?



## jameson_uk (29 Aug 2017)

I am often come across things that say x species is intolerant of organic wastes or you should avoid a build up or organic wastes but this got me thinking as to what they actually were  

I guess I have only really though about waste in terms of the nitrogen cycle and when a fish poops or leaf decays that breaks down to ammonia => nitrite => nitrate...

Are organic wastes just anything containing carbon and if so does that really just mean poop and dead flora / fauna?

Evolution Aqua Pure says it contains Heterotrophic bacteria which consumes organic wastes but presumably as leaves decompose in your tank normally I guess these or similar must be present in the tank anyway?

So given flora, fauna and poop all decompose in the tank, what is it that builds up or is actually bad?  I guess decomposition will consume oxygen so reduce the amount available for fish, plants and nitrification bacteria but this could be counteracted by more surface agitation to keep oxygen levels up?

What am I missing?


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## zozo (29 Aug 2017)

jameson_uk said:


> poop and dead flora / fauna?


 



jameson_uk said:


> So given flora, fauna and poop all decompose in the tank, what is it that builds up or is actually bad?



Next to what you guessed correctly, to much organic waste can become toxic and even pathogenic.


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## ceg4048 (11 Sep 2017)

Hello,
         Organic waste, such as food, poop, urine as well as the waste products excreted by plants, is deadly because bacteria continue to feed and break down these components. The bacteria that perform these functions are aerobic, meaning that they are oxygen breathers. In so doing, therefore, they steal oxygen from your fish and from your plants, leaving the fauna more susceptible to pathogens and leaving the flora more susceptible to algal attacks.

This is the main reason for the advocacy of frequent and large water changes.

Cheers,


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## jameson_uk (12 Sep 2017)

So this is where I appear to be struggling....
If someone said a fish needed highly oxygenated water I can understand that but not being intolerant of organic wastes.

On top of that there appears to be a lot of people advocating not vacuuming the substrate.  Poop, food and plant leaves etc. will tend towards the substrate and when breaking down will provide nutrients (particularly for root feeders?).   Just changing the water will mainly remove what has dissolved into the water column which means the bacteria has already broken the waste down?

Given people add lead litter (which I guess is technically organic waste) then like everything else I am assuming this is just a balancing act.


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## roadmaster (12 Sep 2017)

Easier to remove regularly the solids, dissolved waste's,through water changes,reg maint, than trying to find a perceived balance .


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## ian_m (12 Sep 2017)

Yes the organic waste will rot down to plant food BUT only in low light low tech tanks. This is why some people can go for ever without changing tank water.

In high tech high light tanks the waste is produce too fast for natural processes to harmlessly rot it away to plant food, thus water changes are required.


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## zozo (12 Sep 2017)

It's the small closed invironment which can turn it into a problem if water changes are left out.. Even tho you have flow and a filter, without water changes even with 1m³ water, it is still a closed system. Tolerance and intolerance is very relative and differs enormously among fish sp.. Take for example a Carp, one of the strongest fish around can survive highly eutrophic waters very low in oxygene and rich in organic accumulations and infested with parasites. They are about the last fish to die in such invironments. The Eel is even more resiliant, it literaly lives in organic waste, digs into it and even can survive drouth periods in damp soils. Other fish sp. are highly senstive to polutions or off values like low oxygene. These sp. are used for that by pond owners as indicator sp. A certain kind of Minnow.. I they die, you need to do some checking because there is some sh*t about to hit the fan. And kill everything else if nothing is done.

Anyway an aquarium without water changes is very unnatural.. It doesn't occure in nature, even what we perceive or describe as stagnant bobies of water, actualy are not realy absolute stagnant.. Flow is just a neglectable minimal, not worth mentioning. Real natural stagnant bobies of water are never permanent, only get created after flooding, so if flooding stops and retracts it leaves behind a stagnant pool, but if it is no longer fed with new water. It will slowly drain or evaporate and dry out. (We get our aquarium fish from a lot of these stagnant jungle pools after the flooding periode.)

So every permanent body of water you perceive as stagnant, isn't realy stagnant, it is fed with fresh water from one or several places and it also drains at other places. It must have logicaly or else it can't permenantly excist.  It needs a constant or regular fresh water supply for that and find a healthy balance if it doesn't have it can only accumulate and never flush anything out.. And that is excactly what happens in a fish tank without water changes.. It accumulates, it's a matter of time, not if but when it runs out of control.


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## roadmaster (12 Sep 2017)

I believe given the number's of people who place fishes in their planted affair's,and number's of people who over feed,that the waste from fish food's, and fish poo ,will be primary source of organic waste in closed system mentioned.
Some overfeed more than other's might.have more fauna or less,(balance would be different/fleeting/fluid situation truly)
Would be hard to nail down a balance that might change weekly assuming good plant growth.(more growth,more nutrient's consumed)
We hope decaying plant matter is not produced in excess, lest it indicate something is missing for plant's to do so poorly..
Other's keep plant only tanks and plant's rely on hobbyist to provide primary source of food/nutrient's  along with maybe a little from substrates.
Not as much organic matter created sans fauna.
These are some thing's I have observed in low tech NON CO tanks.
Swap over to high tech,higher light energy, and everything is accelerated, due to more light energy driving plant/fish metabolisim's.
Must be some export mechanisim in closed loop, in addition to plant uptake when everything is running at eleven to keep both plant's and fishes happy.IMHO


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## dw1305 (12 Sep 2017)

Hi all,





jameson_uk said:


> If someone said a fish needed highly oxygenated water I can understand that but not being intolerant of organic wastes.


The real answer is that not all organic wastes are the same.

Dissolved organic carbon compounds (DOC) can be used as a marker of pollution, and the "water" flowing from a landfill, out of a silage clamp or into a sewage works, would be highly polluted with a high BOD (Biochemical Oxygen Demand), high DOC and high TSS (Total Suspended Solids), but these parameters don't necessarily have to occur together. 

This is 50% diluted landfill leachate and gives you an idea of how tinted the full strength leachate is






jameson_uk said:


> Given people add lead litter (which I guess is technically organic waste) then like everything else I am assuming this is just a balancing act


 Yes, the reason that all DOC isn't equal is that, while all life is carbon based, plants also use complex carbohydrates for their structural support. Dead tree leaves, (or bark and wood) are very slow to degrade, because they don't have any of the easily decomposable sugars and proteins, just complex carbon compounds (cellulose, lignin, humic and phenolic compounds) that are resistant to decay. This is why scientists use BOD as a measure of pollution, it can differentiate between easily oxidisable compounds (these have a high BOD) and structural carbohydrates (these have a low BOD). 

In a highly oxygenated, base rich, situation, even if it is nitrogen poor (like the upper layers of lake Tanganyika), the water will have a high degree of clarity, because any dissolved organic carbon compounds (DOC) will oxidise away via microbial action, also a large suite of invertebrates ("detrivores", snails, shrimps etc) will clean up any dead leaves etc. Lake Tanganyika cichlids are often said to be "_intolerant of organic wastes_", and have evolved in an environment where they are only present at very low levels.

You can also have water that is very nitrogen poor with a high level of DOC, usually because conditions are nitrogen poor, acidic and low in oxygen, and these are the conditions that peat forms under in NW Britain. Water flowing through peat (or a stream rich in leaf litter) will pick up DOC and become "black-water", but it will still be low in nutrients and have a low BOD.    

cheers Darrel


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## jameson_uk (17 Sep 2017)

dw1305 said:


> Hi all,The real answer is that not all organic wastes are the same.
> 
> Dissolved organic carbon compounds (DOC) can be used as a marker of pollution, and the "water" flowing from a landfill, out of a silage clamp or into a sewage works, would be highly polluted with a high BOD (Biochemical Oxygen Demand), high DOC and high TSS (Total Suspended Solids), but these parameters don't necessarily have to occur together.
> 
> ...


So one thing that still confuses me is the D...   to become dissolved the decomposition has to have already occurred?   If that is the case then the oxygen used by the bacteria to break down the solids would have already been used?

So for Lake Tanganyika cichlids (and presumably Rainbowfish from fast flowing rivers in Papa New Guinea) the intolerance is actually the level of DOC rather than the need for high levels of oxygen?   The fish might be happier in a sterile tank with some surface agitation than in a heavily planted tank with lots of oxygenation but but lots of poo and decaying plants?


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## techfool (17 Sep 2017)

urea, fish slime, fish scales, hormones, skin cells, mucus, proteins, rotting food and leaves, stuff like that?


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## zozo (17 Sep 2017)

jameson_uk said:


> So one thing that still confuses me is the D... to become dissolved the decomposition has to have already occurred?



I think you kinda misinterpreted dissolved and size, in organic waste.. Take for example Urine which is an organic waste same as a solid turd is, but fluid instead. Fish also secrete fluids containing Ammonia.. Since it is fluid everything in there seems dissolved, it is, but it still is a non processed toxic organic waste and it needs that nitrification cycle before it's contents is converted from amonia into nitrates etc.

http://www.differencebetween.com/difference-between-urea-and-vs-urine/


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## AverageWhiteBloke (17 Sep 2017)

V Interesting discussion, most people assume I guess that anything inside the aquarium will be at some point at one of the stages of the nitrogen cycle and eventually be turned into something else and ultimately degassed as nitrogen or consumed by the plants. Obviously there are further things in there that no amount of filtration or healthy plants could deal with. I think it would be beneficial to members to have a list of what these components are, maybe that would save a lot of confusion over the necessity of the water change if people could say or think they were removing x and not resetting etc.

In the same vein I have often wondered where the plants fit into this? We are often told when growing plants at high rates of growth under high lighting that the plants are also net contributors to the amount of waste in the tank. In which way do the plants contribute to waste levels when it is often said the plants are consuming the waste?


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## zozo (17 Sep 2017)

Next to the obvious sheding/melting dead plant material, a living plants consumes, builds and again secretes such as Oils and proteins, which are partialy again waste products. That famous often discussed surface biofilm is often caused by plant  secretion.


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## zozo (17 Sep 2017)

Maybe the best obvious example of plant secretion we all witness now and then is smelling plants.. Take for example Basil, the air movement from only walking by makes it's leaves brush together and is enough to make it release a load of volatile chemicals. The various essential oils you can buy in the healthshops etc, also contain these volatile chemicals. These are distiled from plantmaterial and concentrated.

These chemicals are released into the atmosphere and you smell it. In an aquarium we also have an atmosphere, but as closed invironment with an steady X volume of water rather a very tiny atmosphere. It has no where else to go, so it all accumulates.

Not all plants smell for us, but it doesn't say they do not release these chemicals among others. I remember Rotala mexicana Goyas, that is a real stinker, smells awfull this little bugger.


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## dw1305 (17 Sep 2017)

Hi all,





jameson_uk said:


> So one thing that still confuses me is the D... to become dissolved the decomposition has to have already occurred? If that is the case then the oxygen used by the bacteria to break down the solids would have already been used?


It is like the others have said, a variety of compounds will be leaking from dead (and living) organisms all the time. 

If we ignore growing plants for a moment, all the easily decomposable metabolites (lipids, ammonia, sugars, proteins) will be rapidly taken up and will fuel microbial growth, depleting oxygen. What is left, after these _low hanging fruit_ have gone, will be the structural carbohydrates, chitin, snail shell etc. which aren't easily broken down and will slowly accumulate.

This also includes the poo you can see, it is fairly inert. Fish don't urinate, as such, either, but ammonia continually diffuses from the fishes gills, you can't see it, but it is the real danger. 





jameson_uk said:


> So for Lake Tanganyika cichlids (and presumably Rainbowfish from fast flowing rivers in Papa New Guinea) the intolerance is actually the level of DOC rather than the need for high levels of oxygen? The fish might be happier in a sterile tank with some surface agitation than in a heavily planted tank with lots of oxygenation but but lots of poo and decaying plants?


No, plants are the easiest way of maintaining high water quality, they are massively net consumers of nutrients (including CO2) and suppliers of oxygen. 

You can use large water changes to maintain water quality, in the same way that you can rely on microbial biological filtration, but water changes combined with plant/microbe filtration is a safer option. 

Some recent research suggests that even the low levels of DOC in "clear water", like sea water, Lake Tanganyika etc. may be important in maintaining fish health. There are references in <"How to remove.....">.

cheers Darrel


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## ceg4048 (18 Sep 2017)

jameson_uk said:


> So one thing that still confuses me is the D... to become dissolved the decomposition has to have already occurred? If that is the case then the oxygen used by the bacteria to break down the solids would have already been used?


It appears that the term "Dissolved Solid" is unclear to many. My guess is that folks often assume that if a solid object, like a sugar cube, is dissolved in a cup of tea, then it's no longer a solid. Of course, it can't be seen so it must not be a solid anymore, it must be a liquid.

if this is the source of confusion, then it is a fundamental misunderstanding.
Have a look at this video:



You can see that the electrical properties of water causes "disassociation" of the components that comprise the solid, but the salt is still a solid.
If you boil the water off the salt will re-appear. 
In order for the salt to be come a liquid, you would have to continue heating it to about 800 degrees C. At that temperature there will be a fundamentl change in the relationship between neighboring atoms that comprise the salt.

It is a similar story with organic proteins and waste molecules. They are considered "dissolved" because the water molecules surround the molecules in a similar fashion.

Bacteria then seek out the molecules and break them apart by chemical means. The oxygen molecules, which are themselves dissolved (and surrounded) in exactly the same way, are also captured by the bacteria and used in the chemical attack upon the solids.

By this method, dissolved gaseous Oxygen is removed from the water and the dissolved solids which are comprised of Nitrogen, Phosphorous, Carbon and other important elements are eaten by the bacteria.

So the answer is NO the breakdown starts once the solids are dissolved, not before.


jameson_uk said:


> The fish might be happier in a sterile tank with some surface agitation than in a heavily planted tank with lots of oxygenation but but lots of poo and decaying plants?


The the one thing most important to fish is dissolved Oxygen, because Oxygen is very poorly dissolved in water and is therefore always is short supply. 

DOC robs the water of Oxygen, so having lots of decaying plant matter and other organic sources is not good. That's why you need to change the tank water as often and as much as feasible, to rid the tank of DOC. This is always going to be true even in your so-called "sterile tank" - and of course this is inaccurate anyway because there will never be any sterile tank, because it will have poop, urine, and uneaten food in it anyway and will require water changes.

In any tank, the imperative will always be to remove DOC, but in a planted tank, which enhances the dissolved Oxygen content by way of photosynthesis, it provides a wider margin of error. Plants also foster the development of aerobic bacteria in the sediment and they oxygenate the sediment as well by manufacturing Oxygen and passing that Oxygen down to the roots. The bacterial chain in the sediment is enhanced and toxins are removed in the sediment in the same way they are removed in the water column and in the filter. So toxic substances from the sediment are less likely to leach into the water column.

Cheers,


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## Daveslaney (18 Sep 2017)

Really interesting thread this,So my guess is proberbly the biggest contributor to DOC in your tank is dirty mechanical filter media in your canister filter?
It is designed to macanically trap waste before it enters the bio stages, But being in a higher pressure envioment the rate it dissolves this waste into the water will be greater? Happen quicker?


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## roadmaster (18 Sep 2017)

Biggest contributor is the waste from fish food's,fish poo,decaying plant matter , which in turn can contribute to dirty filter material.
Hard to have the latter without the former.
Is of little consequence  with weekly water changes and regular filter maint. IMHO


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## dw1305 (18 Sep 2017)

Hi all, 





Daveslaney said:


> So my guess is proberbly the biggest contributor to DOC in your tank is dirty mechanical filter media in your canister filter?
> It is designed to macanically trap waste before it enters the bio stages, But being in a higher pressure envioment the rate it dissolves this waste into the water will be greater? Happen quicker?


The mechanical filtration media will trap particles, how small those particles are will depend on the pore size of the filter material, but these are solid objects, rather than being dissolved. 

A really fine mechanical filter (diatomaceous earth etc), or a chemical media like "Purigen", will also trap colloids, unicellular algae and very fine suspended solids and this will "polish" the water. 

If you have fish food, faeces etc. trapped in the mechanical media some of the more soluble, or easily decomposable, compounds, will enter the water column as DOC or ions, with the remnant left as the ash and structural carbohydrates etc. that don't biodegrade, or are only slowly degraded. The microbial part of the decomposition is dependent upon there being enough oxygen.

We would really like to know both the Biochemical Oxygen Demand (BOD), and dissolved oxygen (%DO) content of our tank water, but they aren't easy to measure.

But if you can get enough oxygen into the water you can process wastes with a huge BOD, this is how the <"activated sludge" process works in waste water treatment">.    

Because we can't get a direct measure of oxygen levels, or BOD, I like techniques that maximise the amount of oxygen in the water, the reason for this is that as long as you have a lot of oxygen, you can deal with a lot of BOD. 

The easiest ways of getting a lot of oxygen in the water are to have growing plants and a very large gas exchange area to water volume ratio. 

If you have a wet and dry trickle filter, or even better a planted wet and dry trickle filter, you have a system that can deal with a huge volume of organic waste, both dissolved and solid (it has a huge gas exchange surface and is extremely difficult to clog). 

If you have a canister filter it a sealed vessel, and a finite amount of oxygen enters the filter. 

If you have your mechanical filtration inside the filter, and use your filter as a siphon (for example if you have floss and don't replace it as frequently as you should) then you run the risk that the biological media will become anaerobic and nitrification will cease, leading to the filter ejecting a stream of de-oxygenated, ammonia rich water.

If you have a planted tank with substrate even this may not prove disastrous, because you have the "belt and braces" of the plants (which produce oxygen and take up ammonia (as NH4+)) and substrate (where nitrification will occur), but if you are entirely reliant on biological filtration in the filter it is game over. 

cheers Darrel


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## roadmaster (18 Sep 2017)

Can smell when canister (s) have been neglected too long and waste collecting there is going/gone rotten.(stinks)
Properly maintained, the media inside smell's like wet dirt = good.
I do not run pre filter's on my community tank,(Turquoise rainbows,celebs rainbows,swordtails) so a few cherry shrimps that live therein, are always found inside the filters when I drain the filter's into bucket for back flushing the eheim 2217's.
They seem to be alive and well living in the canister's, but as mentioned,,I clean the canister's every four week's.
Used HOB aquaclear 110's for year's and media in these was exposed to far more O2 than that found inside sealed canister's.(never rotten smell)
I was one of those who believed that a canister only needed cleaned every few month's, but my fishes seemed to suggest that this was not true.
I keep,breed,trade, longfinned albino Bristlenose in another tank, and this tank needs filter maint nearly every two week's 55 gal with Rena XP3 and aquaclear 802 power head for added water movement near the surface.
Tank holds 1 old Royal pleco,two female and one male Bristlenose,six panda corydoras,and two or three dozen fancy guppies along with gobs of cherry shrimps.(pre filter on intake of this tank)
All tanks get 50 % water change each week.
Maybe twice weekly when baby bristlenose swarms are produced.
Perhaps I keep more fishes than other's so waste is more than other's might see.
Have had nothing but good result's with afore mentioned maint.


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## Bart Hazes (18 Sep 2017)

In our hobby there are many things we don't know but that has never slowed down the stream of opinions as to what is going on and how we should respond. We do that in science and call them hypotheses but an important part is to remember that a hypothesis/opinion is not the answer, just one possible answer. There is a risk that an ad-hoc explanation, especially if repeated again and again in books or internet, becomes the gospel truth and stymies further thought or experimentation on the subject. So kudos for waking us up with this thread.

I consider this thread to be one such topic where the observations are clear but the causes are not. Fortunately, you don't always need to know the details to take appropriate action, but it would be satisfying if we could figure it out someday. To me it is just one symptom of the 'closed system syndrome' where imbalance between things entering and leaving the tank accumulate over time to cause problems. For sensitive fish, or plants, this just shows up earlier. The solution, even if we don't quite know what is the culprit, is to make the system less closed by doing water changes. You can do this on a regular 'preemptive' schedule or you can have some sensitive fish and plants and use them as canaries in the coal mine.


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## AverageWhiteBloke (18 Sep 2017)

Bart Hazes said:


> hypothesis/opinion is not the answer, just one possible answer. There is a risk that an ad-hoc explanation, especially if repeated again and again in books or internet, becomes the gospel truth and stymies further thought or experimentation on the subject.



So true, space weekend was on TV this week. So many references to water being brought to earth riding on the back of Kuiper Belt comets, something that most scientists have stuck to for decades. Following the Rosetta mission it's now seen as highly unlikely as the water on these comets is of a different make up of the water found in our oceans.



Bart Hazes said:


> You can do this on a regular 'preemptive' schedule or you can have some sensitive fish and plants and use them as canaries in the coal mine.



I find with a lot of problems people tend to use the flight and fight mechanism, they see something that sounds like the same problem as they are having and assume they have the same problem and start changing things that didn't need changing. Doesn't help when we are dealing with invisible issues and unreliable means of testing. The mantra has always been listen to the plants but the problem with that is some people don't know what the plant should look like. Some plants even in good health have different colour veins and display different leaf types under certain conditions, that's not to say the plant isn't healthy but most will question iron and magnesium and are they getting enough. If the plant isn't dissolving then it's in relatively good health. We often see plants in showroom condition under optimum conditions but if you check out youtube videos with plants in their natural habitat you will see some do have brown edges or holes in leaves and weird shaped growth, do we question the river its living in?

Coming back to canaries, I've found that adding Duck Weed will tell me far more than anything else I can test or second guess thanks to @dw1305 for some understandable explanations that even an idiot like me can get my head around. If these are doing well even if some other plant isn't at the moment you can pretty much bet you're on the right track and keeping things the way they are the plant that wasn't doing well will often recover over time. I'm also quite shocked after some recent experiences on how little extra fertiliser plants need to thrive in a well established tank.

Regardless of what algae inducing crap is in there it needs to come out and the more wc's the along with good filter maintenance the better. I've found that regardless of what I was dosing the prior will do more for your tank than messing with any nutrients, all you end up doing when messing with your mixes and ratios is masking the underlying issue which is a dirty system. I now dose half of what I used to in the same aquarium with same lighting, co2 etc but increasing cleanliness has made the tank look 10x the tank it was when dosing double the amount of ferts but leaving filter and pipe cleaning until I had to convincing myself that my filter was a nitrate making machine and plants love nitrate. 

I think clarification was needed as too much credence is given and discussed about "re-setting" the tank when dosing EI without mentioning all the other stuff that's in there. Re-setting the tank should take a back seat to the real reason for changing the water, too much emphasis on plenty of co2 and unlimited ferts when it should be on very clean well oxygenated water flowing through clean filter media. Would be nice to say the reason behind the water change is to remove xyz and forget about salt build up which is the least of our worries. In a world of invisible enemies people want something tangible that they can see or feel is working, hence DWI worked for me I guess.

After all these years I still don't really know what's in there, all I know is it needs to come out. I always hark back to a book I read must be 25 years ago which was only a simple thin beginners guide to fishkeeping and two things that I read in there that always stick in my mind were "the solution to pollution is dilution" and "doing a water change is the same as opening a window to let fresh air in" I think when I got into planted tanks that because some of the chemicals I was warned about then were seen as vital now I sort of lost track of my way but now I see it as more important than ever, I got lazy and thought the plants were doing the work which is sort of true but they're only helping.


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## dw1305 (21 Sep 2017)

Hi all, 





roadmaster said:


> Can smell when canister (s) have been neglected too long and waste collecting there is going/gone rotten.(stinks). Properly maintained, the media inside smell's like wet dirt = good.


That is it. The wet earth smell is the aerobic micro-organisms.

If you have rotten smelling media then it has become anaerobic and you can smell a mix of ammonia (NH3) and, if things are really bad, hydrogen sulphide (H2S). There is a fuller description in <"Winogradsky column">.


roadmaster said:


> so a few cherry shrimps that live therein, are always found inside the filters when I drain the filter's into bucket for back flushing the eheim 2217's.  They seem to be alive and well living in the canister's, but as mentioned,,I clean the canister's every four week's.


I've got _Asellus, _snails and Black-worm in mine and they do really well. 





Bart Hazes said:


> There is a risk that an ad-hoc explanation, especially if repeated again and again in books or internet, becomes the gospel truth and stymies further thought or experimentation on the subject. So kudos for waking us up with this thread.


That is really the problem with discussion of biological filtration on forums, lots of people hold "faith" positions and there isn't a willingness to engage with new research or new ideas.

I think I'm right, but I don't have any empirical evidence of suitable scientific rigor. The problem with ecology (and that is really what we are talking about) is that there are a lot of "grey" areas, with a huge number of variables. You can build a model of what you think is happening, but your model is only as good as the data you put in.





AverageWhiteBloke said:


> Doesn't help when we are dealing with invisible issues and unreliable means of testing. The mantra has always been listen to the plants but the problem with that is some people don't know what the plant should look like. Some plants even in good health have different colour veins and display different leaf types under certain conditions, that's not to say the plant isn't healthy but most will question iron and magnesium and are they getting enough. If the plant isn't dissolving then it's in relatively good health.


I just want some growth out of my plants, I don't really want them growing optimally, I just want them growing. If the growth rates of the non-CO2 limited plants suddenly increase I know that I have more of the limiting nutrient, probably usually nitrogen in my tanks.





Bart Hazes said:


> To me it is just one symptom of the 'closed system syndrome' where imbalance between things entering and leaving the tank accumulate over time to cause problems. For sensitive fish, or plants, this just shows up earlier. The solution, even if we don't quite know what is the culprit, is to make the system less closed by doing water changes. You can do this on a regular 'preemptive' schedule or you can have some sensitive fish and plants and use them as canaries in the coal mine.


The canary aspect is covered to some degree in <"Do I need to cycle....">, which has many of the same posters as this thread.





AverageWhiteBloke said:


> Coming back to canaries, I've found that adding Duck Weed will tell me far more than anything else I can test or second guess thanks to @dw1305.


 I want people to use floating plants, and the "Duckweed Index", not only because it massages my ego, but because I'm sure that it makes tank management easier.

This works on the assumption you have sufficient PAR, but it is a simple set of rules, if your "Duckweed" (usually _Limnobium_ for me, although _Lemna minor_ would be more responsive to deficiencies of non-mobile nutrients like iron (Fe), because of its quicker potential growth rate) is green and growing (however slowly) just carry on as normal. If it turns yellow, or stops dividing, add a small amount of fertiliser. If I add potassium nitrate (KNO3) that covers the two macro-nutrients that plants need most of. If you don't get a fairly instant greening (they are mobile within the plant), you could add all the other nutrients one at a time, but I just add a complete fertiliser at that point.

I don't need to know which the limiting nutrient is, I just need to raise the level of it. 





AverageWhiteBloke said:


> After all these years I still don't really know what's in there, all I know is it needs to come out.


 I don't know either, and I'm not sure anybody else knows. Even if we just look at ions,  I used conductivity is a base-line datum, because it is easy to measure and is a linear measurement across a whole range of water types, but the problem is that every-bodies baseline will be different.

For me I know that about 80 - 150 microS in the tanks is the range I want, but I don't know what those constituent ions are. If I used our hard tap water, rather than rain-water, in the tanks I would need to add ~400microS to take into account the carbonate hardness.

cheers Darrel


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## Bart Hazes (21 Sep 2017)

dw1305 said:


> ... text removed ...
> I want people to use floating plants, and the "Duckweed Index", not only because it massages my ego, but because I'm sure that it makes tank management easier.
> 
> This works on the assumption you have sufficient PAR, but it is a simple set of rules, if your "Duckweed" (usually _Limnobium_ for me, although _Lemna minor_ would be more responsive to deficiencies of non-mobile nutrients like iron (Fe), because of its quicker potential growth rate) is green and growing (however slowly) just carry on as normal. If it turns yellow, or stops dividing, add a small amount of fertiliser.
> ...



I tend to harvest floaters if the Limnobium turns yellow to better match the plant biomass to the waste production of the fauna in the tank. Fertilizer would work to green the floaters but I have too many already so I (and my composting worms) am always happy if it time to harvest.


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## Soilwork (22 Sep 2017)

Great discussion.  I have to say that I stopped using a canister filter opting for a surface skimmer to tackle the biofilm. I figured my substrate would take care of the nitrification side of things. 

Finally after Cyanobacteria showed up (again) I decided enough was enough and began to change water and lots of it.  I installed a canister filter with spraybar and for the first time in a while a have new growth from my plant.  Further more the cyano is residing and biofilm takes much longer to form.  My thoughts would be cyano contribute heavily to the biofilm.  My substrate was very dirty on top and the compounds within would surely be contributing too. 

The tank in the attached picture suffered from every algae imaginable for the first 6 months then I decided to get my act together.  Again I purchased a spray bar and a second internal filter and began to change water. The biofilm disappeared and the surface was almost mirror like and he plants exploded.  The substrate was soil.  I wasn't using micro ferts just NPK no calcium or magnesium. 

My only thoughts are if oxygen is low for microorganisms would this not become apparent sooner via larger organisms like fish, snails and shrimp? Secondly when I did eventually tear the tank down the substrate smell was horrendous yet the health of the plants is undeniable so I would say that these smelly processes may be beneficial if not necessary in a well established substrate and tank.


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## dw1305 (22 Sep 2017)

Hi all, 





Soilwork said:


> Secondly when I did eventually tear the tank down the substrate smell was horrendous yet the health of the plants is undeniable so I would say that these smelly processes may be beneficial if not necessary in a well established substrate and tank.


Yes, it is fine in the substrate, essential plant nutrients like iron (Fe++) will become available in the anaerobic zones with negative REDOX values. 

You will always get a zonation of REDOX values in a tank with rooted plants, and near plant roots (and the substrate surface) you will get <"zones of fluctuating REDOX">, which maybe particularly important for plant nutrient availability. 

You can also get a similar zonation in a mature <"Hamburg Matten Filter">, or even a wet and dry trickle filter.
http://www.swisstropicals.com/library/aquarium-biofiltration/
The difference between substrate, matten filter and a canister filter is that in the canister filter you have a finite amount of oxygen, whereas the substrate and HMF filter plate have access to oxygen from the water column. 

Trickle filters have the added advantage of having access to atmospheric oxygen, meaning that you can use them to treat liquid wastes with a huge BOD (this is how the older style sewage treatment beds work).

cheers Darrel


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## dan4x4 (27 Sep 2017)

Reading this thread is really interesting. Thanks for everybody's input.


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## jaypeecee (9 Oct 2019)

Hi Folks,

What an interesting thread! I have a few questions:

[1] Should we use _liquid_ (biological) organic waste removers to help break down organic waste on the substrate?

[2] Should we use organic waste removers inside the filter (e.g. Purigen, Renew) to, for example, reduce the frequency of water changes?

[3] Do adsorbing organic waste removers inside the filter release compounds (e.g. nitrates, phosphates) back into the water?

[4] Do plants suffer if dissolved organic compounds (DOCs) are removed from the water column? (I have in mind ferrous gluconate).

That'll do for the moment!

JPC


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## jaypeecee (9 Oct 2019)

jameson_uk said:


> On top of that there appears to be a lot of people advocating not vacuuming the substrate.



Isn't the thinking there that heterotrophic bacteria in the substrate may get released into the water column and become dominant over autotrophic nitrifying bacteria in the filtration system? As I understand it, heterotrophic bacteria multiply rapidly in stark contrast to autotrophic bacteria. The trick is to vacuum only the _surface_ of the substrate - easier said than done if you're using sand!

JPC


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## jaypeecee (19 Oct 2019)

Hi Folks,

Anyone got any answers to the questions that I posed above?

*P-l-e-a-s-e!*

JPC


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## jaypeecee (19 Oct 2019)

dw1305 said:


> The easiest ways of getting a lot of oxygen in the water are to have growing plants and a very large gas exchange area to water volume ratio.



Hi Darrel,

Whilst the gas exchange area to water volume is essentially constant for a given tank, the oxygen contribution of growing plants surely only applies during the day. At night, the situation reverses and plants absorb oxygen from the water. But the breaking down of organic waste presumably takes place 24/7. So, dissolved oxygen will reduce overnight.

JPC


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## sparkyweasel (19 Oct 2019)

jaypeecee said:


> Isn't the thinking there that heterotrophic bacteria in the substrate may get released into the water column and become dominant over autotrophic nitrifying bacteria in the filtration system? As I understand it, heterotrophic bacteria multiply rapidly in stark contrast to autotrophic bacteria. The trick is to vacuum only the _surface_ of the substrate - easier said than done if you're using sand!
> 
> JPC


Surely any bacteria etc disturbed would be syphoned out as you vacuum? But mostly they would stay attached to the substrate. Bacteria can stick to the sand in a fluidised bed filter, so I don't think a gravel vac would loosen many of them.


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## dw1305 (19 Oct 2019)

Hi all, 





jaypeecee said:


> [1] Should we use _liquid_ (biological) organic waste removers to help break down organic waste on the substrate?


You don't need anything, particularly if you have plants rooted in the substrate, roots are <"leaky structures">. You can get "sludge buster" type bombs and treatments, they are designed for use septic tanks, but they have a following amongst people who keep <"ponds etc.">. I can't imagine any use for them in the planted aquarium. 





jaypeecee said:


> [2] Should we use organic waste removers inside the filter (e.g. Purigen, Renew) to, for example, reduce the frequency of water changes?


 If you have enough oxygen you should get <"complete oxidation">.  I'm not a fan of chemical media and I like water changes. 





jaypeecee said:


> Do adsorbing organic waste removers inside the filter release compounds (e.g. nitrates, phosphates) back into the water?


Yes, they could do if they, but it would be more likely that they would just stop being active. Ion exchange resins definitely could begin to exchange (formerly bound) ions back into the tap water, but ion exchange depends on both the position of the ion on the <"lyotropic series">, and their concentration.





jaypeecee said:


> Do plants suffer if dissolved organic compounds (DOCs) are removed from the water column? (I have in mind ferrous gluconate).


It would only really be chelated compounds that were retained, have a look at <"Fe EDDHA">. 





jaypeecee said:


> Isn't the thinking there that heterotrophic bacteria in the substrate may get released into the water column and become dominant over autotrophic nitrifying bacteria in the filtration system? As I understand it, heterotrophic bacteria multiply rapidly in stark contrast to autotrophic bacteria. The trick is to vacuum only the _surface_ of the substrate - easier said than done if you're using sand!


I'd have to say I'm sceptical, the microbial assemblage will vary dependent on the amount of food. If you have a <"bacterial bloom"> it is because you have the "low hanging fruits" of easily available sugars and proteins. I don't vacuum my substrate, but I do occasionally syphon dead leaves etc from the sand surface. The possibility of organic waste blocking the filter is the reasons that I only want ammonia and oxygen entering the filter. 





jaypeecee said:


> Whilst the gas exchange area to water volume is essentially constant for a given tank, the oxygen contribution of growing plants surely only applies during the day.


Yes and no. In a non-planted tank it is always night. This is because plants are massively contributors to net oxygenation. One molecule of oxygen is evolved for every molecule of CO2 absorbed, and plants grew. That growth is the carbon that ends up as plant tissue, rather than CO2.

The other reason is that the <"plants internal spaces"> are saturated with oxygen at the end of the photo-period, and it is largely this oxygen that the plant utilises at night. 





jaypeecee said:


> At night, the situation reverses and plants absorb oxygen from the water. But the breaking down of organic waste presumably takes place 24/7. So, dissolved oxygen will reduce overnight.


It will. If you had a tall tank with a large bio-load and relatively small gas exchange surface  you might have issues at night, even with plants and a large capacity canister filter.

cheers Darrel


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## jaypeecee (19 Oct 2019)

sparkyweasel said:


> Surely any bacteria etc disturbed would be syphoned out as you vacuum? But mostly they would stay attached to the substrate. Bacteria can stick to the sand in a fluidised bed filter, so I don't think a gravel vac would loosen many of them.



Hi,

I agree with everything that you have said. Someone on a well-respected forum wrote an extensive article suggesting that it was wrong to disturb the substrate and to use bacterial supplements to help break down organic waste. And this was because of concern that heterotrophic bacteria would take over. When I have a moment (!), I will try to find that article. I sent a PM to that person challenging them to support what was being said but never got a reply.

JPC


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## jaypeecee (19 Oct 2019)

Hi Darrel,

I am very grateful for your comprehensive reply - thank you!

You have answered all my questions and there is one gem of information in your reply where you said:

"The other reason is that the <"plants internal spaces"> are saturated with oxygen at the end of the photo-period, and it is largely this oxygen that the plant utilises at night".

I was not aware of this.

With reference to my question [2], my understanding of Seachem _Renew_ is that its mode of action is more akin to a molecular sieve than an ion exchange resin. That's what Seachem told me when I contacted their Technical Support team recently. But my background is in physics and the term 'molecular sieve' was new to me.

Thanks again.

JPC


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## Edvet (20 Oct 2019)

jaypeecee said:


> more akin to a molecular sieve than an ion exchange resin.


Not sure that isn't just "big words" to sell a product, more then an actual description.
Talking about a molecular sieve i think of semipermeabele membranes (RO), not something sitting in a solution. Maybe the molecule exchange in a biological film, as in all our filtres happens, is what happens.


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## dw1305 (20 Oct 2019)

Hi all, 





jaypeecee said:


> my understanding of Seachem _Renew_ is that its mode of action is more akin to a molecular sieve than an ion exchange resin. That's what Seachem told me when I contacted their Technical Support team recently. But my background is in physics and the term 'molecular sieve' was new to me.


I'd be honest and say that this is the first time I've come upon <"Seachem Renew">. 

The "molecular sieve" bit means that it trapping molecules with a certain size This could be an entirely physical process (like if you used a diatom filter) or by chemical means (like Purigen) or a combination of both.  By the look of the description it retains molecules that are bigger than those trapped by Activated Carbon or Purigen.  I can't tell you exactly what Renew is, it looks to be another rock of <"volcanic origin">.





Edvet said:


> Not sure that isn't just "big words" to sell a product, more then an actual description.


It looks like another Seachem classic, they don't actually tell you what it contains or how it works. The phosphate bit is just a total red herring, you have to admire their chutzpah. It isn't a product that is going to have any effect of phosphate levels. PO4--- is an ion, and orders of magnitude smaller than the compounds this will filter out, but you set up a paper tiger and then you demolish it. 

I'm going to have a go: 





> "Darrel's Amazon Frogbit will protect you against werewolves, other floating plants may be attractive to werewolves, but this will never be an issue with Darrel's Amazon Frogbit".


cheers Darrel


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## jaypeecee (20 Oct 2019)

Hi Darrel,

I did manage to find out about molecular sieves. Wikipedia described them as follows:

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

I guess that the dissolved organics from organic waste are much larger than water molecules. So, water freely passes through the Seachem _Renew_ and dissolved organics are retained. That being the case, would that mean that nitrifying and other bacteria can't get to work on these tasty morsels? If they can, then the organic waste would be broken down inside the filter and that would seem to be counterproductive, wouldn't it? Or maybe not.

To be fair to Seachem (or, indeed, any other manufacturer), I can understand them not wanting to say what _Renew_ contains. Proprietary information, trade secrets and all that. I like your advertising slogan for _Darrel's Amazon Frogbit_. Excellent!

JPC


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## Zeus. (20 Oct 2019)

jaypeecee said:


> Proprietary information, trade secrets and all that.



Which translates to trade secrets, profit, failure to give the facts and data to support their claim, holding back science. "Data on file" is what we see company's in my field use to hide the evidence of their claims for their products, which to me means weak unsubstantial results with resulting graphs without fields


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## jaypeecee (20 Oct 2019)

jaypeecee said:


> So, water freely passes through the Seachem _Renew_ and dissolved organics are retained. That being the case, would that mean that nitrifying and other bacteria can't get to work on these tasty morsels? If they can, then the organic waste would be broken down inside the filter and that would seem to be counterproductive, wouldn't it? Or maybe not.



I think I may have answered my own question. Seachem has this to say:

"Renew™ will remove organics and particulates in the sub-micron range; it will also help control ammonia, nitrates, and phosphates".

I think what Seachem are saying here is that ammonia, nitrates and phosphates are not produced inside the filter as a result of adding _Renew_.

As Monty Python used to say - my bwain hurts! (Spelling error intentional)

JPC


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## sparkyweasel (20 Oct 2019)

dw1305 said:


> I can't tell you exactly what Renew is, it looks to be another rock of <"volcanic origin">.


Good guess 
According to the data sheet, it's pumice.
https://www.dropbox.com/sh/iu6wapsz...74YoOLmTa?dl=0&preview=Renew+SDS+20160111.pdf


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## jaypeecee (20 Oct 2019)

sparkyweasel said:


> Good guess
> According to the data sheet, it's pumice.
> https://www.dropbox.com/sh/iu6wapsz...74YoOLmTa?dl=0&preview=Renew+SDS+20160111.pdf



Great bit of detective work, sparky.

I never thought to look at the MSDS. As you say, it's nothing other than (very expensive) pumice! I'll try to obtain a much cheaper source of this stuff.

JPC


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## Edvet (20 Oct 2019)

Now that's something worthy of a download, thx sparkyweasel


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## dw1305 (20 Oct 2019)

Hi all,





jaypeecee said:


> I guess that the dissolved organics from organic waste are much larger than water molecules. So, water freely passes through the Seachem _Renew_ and dissolved organics are retained.


Yes I'm sure that's it, they must be larger pores than you find in Purigen.





jaypeecee said:


> That being the case, would that mean that nitrifying and other bacteria can't get to work on these tasty morsels? If they can, then the organic waste would be broken down inside the filter and that would seem to be counterproductive, wouldn't it? Or maybe not.


It doesn't really matter where nitrification takes place. 





sparkyweasel said:


> According to the data sheet, it's pumice.


That was my guess, and I'd also be willing to speculate that it comes from the same mine as "Matrix", and the deposits are *very close* together. 





jaypeecee said:


> I like your advertising slogan for _Darrel's Amazon Frogbit_. Excellent!


I already have a testimonial. A certified customer has contacted the, premium rate, help line with this message.





> ........I used to lose all my fish every month and then have to go and buy new ones. I'd never heard about werewolves but once I realised that they come out once a month, and that was when my fish died, the penny dropped and I thought I'd give "*Darrel's Frogbit*" a go.
> 
> Boy am I pleased I did, two months on no more fish deaths and its all down to the werewolf repellent properties of "*Darrel's Frogbit*".......


cheers Darrel


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## sciencefiction (20 Oct 2019)

Something I didn't see being mentioned is the actual pathogenic and non-pathogenic assembly of micro-organisms in a tank. From what I have read in studies on microbial assembly in aquaculture systems, the majority of pathogens detected populate mainly the water column. Doing sufficient water changes doesn't just remover organics but the actual pathogenic bacteria that is dangerous to fish if in prevailing numbers. The filter media itself  or the substrate is a different situation as microbes work in symbiosis with each other and it is normal and healthy to have all type of microbes in there, unlike what you want in the water column where pathogens pose an immediate danger to fish. Hence chemical media is useless as it does not target pathogens, and skipping the water change means increased pathogenic load.

I personally never worry if I have siphoned the substrate, unless there is visible detritus, or even if I have cleaned the filter, although I do use pre-filters on the intakes that are regularly washed. I concentrate on doing large enough and regular water changes along with maintaining growing plants or some sort, and it does not fail me as far as fish health is concerned.


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## jaypeecee (21 Oct 2019)

sciencefiction said:


> Something I didn't see being mentioned is the actual pathogenic and non-pathogenic assembly of micro-organisms in a tank. From what I have read in studies on microbial assembly in aquaculture systems, the majority of pathogens detected populate mainly the water column. Doing sufficient water changes doesn't just remover organics but the actual pathogenic bacteria that is dangerous to fish if in prevailing numbers.



Hi SF,

Whilst I am very aware of pathogenic organisms that inhabit the water column, to which non-pathogenic organisms are you referring? Partly my reason for asking is that I have been considering the purchase of a UV-C sterilizer to kill off pathogens but I wouldn't want this to harm non-pathogenic organisms.

JPC


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## sciencefiction (21 Oct 2019)

jaypeecee said:


> Hi SF,
> 
> Whilst I am very aware of pathogenic organisms that inhabit the water column, to which non-pathogenic organisms are you referring? Partly my reason for asking is that I have been considering the purchase of a UV-C sterilizer to kill off pathogens but I wouldn't want this to harm non-pathogenic organisms.
> 
> JPC



Right now I am talking from the top of my head but you can read on biofloc technology studies for more details. Biofloc technoloy is a type of non-water changed aquaculture system that tries to achieve nature in a closed system.

 Non-pathogens could be pretty much anything, certain protozoa, nematodes, other bacteria, etc..From all those there are some dangerous to fish and some harmless.
I wouldn't worry about killing non-pathogenic organisms in the water column because the ones that matter inhabit the filter/substrate, according to studies. The assembly of micro-organisms in the water column apparently changes throughout the day and can be influenced by many factors, as simple as what type of food one fed the fish today. In fact, feeding certain foods apparently can enhance the prevalence of certain organisms.

On another hand,they say the assembly of micro-organisms in the filter is fairly constant. 

Since none of us owns the technology to test our tank water on a daily basis for the type of micro-organisms that are prevailing in certain scenarios, and science is still not advanced enough on the topic, it is best to keep the water clean, via water changes being the easiest but I suppose a UV sterilizer can also help. I personally think it's too much trouble as it doesn't guarantee it would be effective against all type of pathogens where a large water change would certainly reduce the amount of anything floating in the water column to a minimum, plus reduce other toxins.  A tank is never sterile,and can never be but it is possible to keep the water fairly clean, enough so fish's immune system can cope with any minor stuff. 

I think the key of understanding how to achieve nature in aquariums is studying those micro-organism and learn how to influence them to our advantage. So far science has been very poor. We have only recently made some leaps on the type of nitrifiers that get established in aquariums after false beliefs for decades(i.e. archaea) I personally believe that one day it will be possible to purposely set up and "maintain" an aquarium without water changes but right now without advanced knowledge available, if one strikes that balance, it is like winning the lottery. Whoever figures it out fully and is able to reproduce that system again and again, achieving healthy and vibrant fish, can get rich....All fish farms are trying to get there right now as the dangers of the usage of antibiotics on fish for human consumption is being highlighted and water changes on a large scale is not just expensive, it is dangerous, as one can pass on aquaculture microbes to the environment.


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## jaypeecee (22 Oct 2019)

sciencefiction said:


> Biofloc technoloy is a type of non-water changed aquaculture system that tries to achieve nature in a closed system.
> 
> Since none of us owns the technology to test our tank water on a daily basis for the type of micro-organisms that are prevailing in certain scenarios, and science is still not advanced enough on the topic, it is best to keep the water clean, via water changes being the easiest but I suppose a UV sterilizer can also help. I personally think it's too much trouble as it doesn't guarantee it would be effective against all type of pathogens where a large water change would certainly reduce the amount of anything floating in the water column to a minimum, plus reduce other toxins.



Hi SF,

Thanks for the feedback.

I hadn't heard of biofloc technology so will do some reading.

The idea of tank water being treated by UV-C is appealing to me in the sense that 100% of the water passes through the UV-C sterilizer. We can't do, and wouldn't want to do, 100% water changes. Not only should a UV-C sterilizer kill off pathogenic bacteria but it should also kill fungal spores and algae spores. I have selected one for the size of my tank and flow rate. I just need to make the purchase.

I hope I haven't given the impression that I'm not in favour of water changes. On the contrary, I do water changes but I don't have a strict regime.

JPC


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## ian_m (22 Oct 2019)

Read this about dwell time. Most hobby grade UV units have insufficient dwell time to work thoroughly.

http://www.americanaquariumproducts.com/AquariumUVSterilization.html


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## jaypeecee (22 Oct 2019)

ian_m said:


> Read this about dwell time. Most hobby grade UV units have insufficient dwell time to work thoroughly.
> 
> http://www.americanaquariumproducts.com/AquariumUVSterilization.html



Hi Ian,

I've read Carl Strohmeyer's article above. And, of course, what he says is correct. But I've done my research and I've got my fingers crossed.

JPC


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## jaypeecee (22 Oct 2019)

Hi Folks,

It has just occurred to me that here we are discussing organic waste and dissolved organic compounds (DOCs) but I don't think we've mentioned Oxidation-Reduction Potential (ORP) or Redox. As measuring biological oxygen demand (BOD) is not easy, we do have the option to measure ORP. The more waste in the tank, the lower the ORP thus making ORP a very useful water quality indicator (along with other parameters of one's choosing). Some time ago, I used to do this. So, I'll dig out my results and report back. I do also measure dissolved oxygen from time to time.

But I would also like to know where humic substances fit into this. They are organic compounds but they have been shown to be beneficial in aquaria so we wouldn't want to remove them. What effect do they have on ORP?

JPC


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## dw1305 (22 Oct 2019)

Hi all, 





jaypeecee said:


> But I would also like to know where humic substances fit into this. They are organic compounds but they have been shown to be beneficial in aquaria so we wouldn't want to remove them. What effect do they have on ORP?


They don't have very much. It is back to the ease with which <"compounds are broken down">, there is very little energy gain in degrading these compounds, so they don't support much microbial biomass.

If you look at a blackwater river (like the Rio Negro) it has very low conductivity and microbial load. 





jaypeecee said:


> I don't think we've mentioned Oxidation-Reduction Potential (ORP) or Redox


It is a little bit open to interpretation. Have a look at <"A question.....">.

cheers Darrel


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## jaypeecee (26 Oct 2019)

jaypeecee said:


> ...we do have the option to measure ORP. The more waste in the tank, the lower the ORP thus making ORP a very useful water quality indicator (along with other parameters of one's choosing). Some time ago, I used to do this. So, I'll dig out my results and report back.



Hi Folks,

I had a look over my ORP measurements from a 125 litre planted community tank. I recorded measurements from Feb 2018 to June 2018. Initially, the average ORP was +240mV with the odd increase to +350mV. Then, in April 2018, I changed the filter from a JBL i80 internal unit to an Eheim Ecco Pro 130 external unit. Initially, the readings were around +220mV. Then, from late May, the readings were more variable - ranging from +320mV to +512mV. It is difficult to pin down the cause of these fluctuations. I checked the calibration of my ORP meter from time to time using the Pinpoint +400mV solution.

JPC


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## jaypeecee (12 Feb 2021)

dw1305 said:


> We would really like to know both the Biochemical Oxygen Demand (BOD), and dissolved oxygen (%DO) content of our tank water, but they aren't easy to measure.


Hi Darrel,

I like to use an ORP/Redox meter for this purpose. From lots of empirical data, my experience is that ORP gives a quick-and-easy indication of dissolved oxygen/BOD. The meter dangling into the tank in the following thread is actually measuring ORP, not pH as the meter would have you believe!






						Aquarium Plant Fertilizers - Sources of Nitrogen
					

Hi Everyone,  Ever since reading Diana Walstad's Ecology of the Planted Aquarium book on the topic of most plants preferring ammonium over nitrate, I have been digging deeper into this. And, I have found some interesting stuff that I'd like to share. In particular, I have been drawn to the use...



					www.ukaps.org
				




JPC


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## dw1305 (12 Feb 2021)

Hi all, 


jaypeecee said:


> I like to use an ORP/Redox meter for this purpose.


It will work. 

They had a bit if a vogue in <"Rift Lake Cichlid keeping circles">, a thread I think we both contributed to. 

cheers Darrel


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