# Water changes bad for beneficial bacteria



## jameson_uk (12 Feb 2021)

Headline for attention but someone posted on another forum that a friend was suggesting their twice weekly 50% water change schedule would be bad as it would starve the beneficial bacteria of ammonia and they would end up needing to leave the tank to stabilise.

Got me thinking of two things...
First off is how long ammonia exists on the aquarium. Given that people dose 2ppm+ when _cycling_ and expect it to be gone in 24 hours and whenever you measure it we expect it to be zero suggests that it is consumed pretty quickly.

The second is how long BB can survive without ammonia. I know there are a couple of threads which say that it needs oxygen to survive but I couldn't find anything that suggested how long they would last without _food_.

I know plants play into this as I guess in a heavily planted tank the ammonia rarely makes it to nitrification and is consumed by the plants before then. How would this differ in a non planted tank?


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## jaypeecee (12 Feb 2021)

Hi @jameson_uk 

If I were to go through my collection of scientific papers on this topic, I could probably give you a detailed reply. But, this is one of those situations where I prefer to turn this around and ask the person who first proposed this idea to substantiate this suggestion. Otherwise, _in my opinion_, this is just hearsay.

JPC


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## jameson_uk (12 Feb 2021)

jaypeecee said:


> Hi @jameson_uk
> 
> If I were to go through my collection of scientific papers on this topic, I could probably give you a detailed reply. But, this is one of those situations where I prefer to turn this around and ask the person who first proposed this idea to substantiate this suggestion. Otherwise, _in my opinion_, this is just hearsay.
> 
> JPC


Totally. This was more that is piqued my interest. Particularly when you think the standard view is that ammonia should never show up but it must constantly be being added to the tank.


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## zozo (12 Feb 2021)

The only thing that could be of an issue is if the tap water has Chlorine in it, this is a disinfectant added to tap water by the water company to sterilize it. So if it contains this it could also kill bacteria in the tank and even have an ill effect on the livestock. Thus you should make sure that this isn't in the water.

The beneficial bacteria responsible for the nitrogen cycle are mainly living and find their food in the substrate, in and around the plant roots and in the biofilm that develops on the glass and hardscape. They are not really happily free swimming around in the water column. There is nothing for them to find in the water...  Thus you can water change as much as you like it will have no ill effect on the bacteria as long as it is healthy clean water.

Decaying organic material, leftover fish food and fish poop contains ammonia, how much, and how long it takes for the bacteria to convert it is hard if not impossible to determine... But since all this material sinks down into the substrate and starts its decomposing process there, than also all available ammonia will mainly be in the substrate. Very little will leach back into the water column. If you reach a point that ammonia is measurable in the water column it means the substrate is much too dirty or mechanically disturbed (by hand).

Thus as long as you do not have too much measurable ammonia in the water column than how long it takes for the bacteria to convert what's in the substrate is rather irrelevant. There is nothing for you to worry about.


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## jaypeecee (12 Feb 2021)

jameson_uk said:


> Particularly when you think the standard view is that ammonia should never show up but it must constantly be being added to the tank.


Absolutely.


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## Tim Harrison (12 Feb 2021)

There is an old skool idea that water changes will rob beneficial bacteria of ammonium, and therefore stall the cycling process...


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## jaypeecee (12 Feb 2021)

jameson_uk said:


> Headline for attention but someone posted on another forum that a friend was suggesting their twice weekly 50% water change schedule would be bad as it would starve the beneficial bacteria of ammonia and they would end up needing to leave the tank to stabilise.


Hi again,

I was responding specifically to the above. But, @zozo is obviously correct. Indeed, it extends beyond chlorine to chloramine, which is increasingly used by water companies. So, perhaps the original suggestion from the friend had been misunderstood.

JPC


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## John q (12 Feb 2021)

Regards bacteria survival without ammonia it probably depends on which scientific paper you read. I'm not sure how closely related _Nitrosospira briensis_ is to aquarium bacteria but apparently that can survive for 10-14 days. 
Hopefully someone with more understanding than I can clarify.

Cheers.


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## sparkyweasel (12 Feb 2021)

So, if you reduce the amount of ammonia (by water changes) the population of BB will reduce.
But with less ammonia you need fewer BB to deal with the ammonia. No problem.
If the ammonia creeps up again the BB will enjoy a population explosion. Some bacteria can double their numbers in 20 minues if there is sufficient food.
Once established, the population of BB will fluctuate with the food supply and there will always be enough under normal conditions.


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## tam (13 Feb 2021)

Does it matter? Either you are removing it through water changes or bacteria via the nitrogen cycle. As long as it's not there, who cares. If there is ever enough inbetween changes to support bacteria it will develop, and if there isn't it's not needed anyway.


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## Soilwork (13 Feb 2021)

The only way water changes will disrupt your microbial assemblage is through chlorine or chloramine.  Maybe in another few years pesticides.  

Ive never had any problems since switching to rain water.


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## Mark Nicholls (13 Feb 2021)

I would suggest that any Ammonia added as part of an EI regime is EXTRA to that produced by tank inhabitants. 
The bacterial colony in a filter has a constant supply of food as the amount of waste produced by fish stays the same.
Any Ammonia added as part of an EI regime WOULD be consumed by BB but there will ALWAYS be a small surplus until the 50% water change is done.


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## shangman (13 Feb 2021)

When I started fishkeeping I read this in several places, in relation to a Walstad tank which is what I intended to start with. Not doing water changes (plus adding ammonia, craziest advice ever ) killed my first fish. I think things like that can be done by some people, but certainly not by beginners, and I don't like that it demonises water changes which are the number 1 thing to do weekly + when things go wrong. It's literally a dangerous idea for those unlucky first fish.

I'm still obsessed with the idea that were should chuck the term of cycling for new people and change it to maturing, to emphasise that time and growth of plants + bacteria is most important, rather than the abstracted scientific process of cycling which confuses beginners and makes them think they can cheat and speed things up by fiddling and doing excessive am/no/na tests. Not to say we shouldn't mention how the process works, but deemphasize people's control over it and myths about it like the water changes. Been thinking about working on a little ukaps foolhardy beginners guide to tropical aquariums, I go on a few forums and am often giving advice (basically just the above + use more plants) to newbies who are confused and have been given terrible advice from online +lfs


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## John q (13 Feb 2021)

I seem to say this a lot but sorry to the Op for going off topic.



shangman said:


> Been thinking about working on a little ukaps foolhardy beginners guide to tropical aquariums.



On the surface I think this is a brilliant idea but we have to have a degree of acceptance that there are different ways in which to cycle/mature aquariums. 

In terms of planted tanks the holy grail would be to start with a high plant mass and ideally some fast growing stem plants, then after maybe six weeks livestock would be slowly added.
At the opposite end of the spectrum would be a tank set up from day one, overly stocked with fish and a single anubias nana petite, which technically for the sake of this example is a planted tank.

We should also consider the elephant in the room that is TESTING! We all know these kits aren't accurate but lots of us do it in secrecy, fearing ridicule if the secret ever gets out. When starting a tank how do we know when its safe to add fish if we don't at some point test for ammonia? 

So yes a guide would be useful, but I think it should be approached with "Harm reduction" in the back of our minds and not a preached sermon of A is right and B is wrong.

Cheers.


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## shangman (13 Feb 2021)

John q said:


> I seem to say this a lot but sorry to the Op for going off topic.
> 
> 
> 
> ...


Oh goodness I hope I haven't opened a can of worms I didn't mean to!! It doesn't have to be for UKAPs, I was just thinking of writing on my own as a side thing during corona and seeing if it could help people. Obviously UKAPs is full of people with experience who love their hobby, so it's not really the target audience, but we do get beginners who do need some help. A big emphasis would be on researching more (like during those 6 weeks working out what fish would actually be right for people's tanks), and looking at journals here and things.

My plan for a guide was because people (including me) kill their fish when they start completely accidentally, they've got dodgy info from their LFS which they trusted (my LFS is great but not all are), or they did loads of research online and found conflicting information so just picked one (often the wrong one). I never found a how-to guide that comprehensively explained things to a complete beginner, I did everything I thought was correct, but it wasn't. It wasn't until I came here that I started to understand things better, and see the aquarium as a whole system. So my thought was to write a guide for me when I started basically lol

It would explain basic concepts in a clear way, with examples for how people can do things, with links for extra reading on different topics, but always being clear what is essential an what is optional, and what is something for a complete beginner vs someone who has experience. Obviously there are many different ways of doing things, but I think picking one way (6 weeks maturation with heavy planting from the start & substantial regular water changes) is the best way for beginners to set them up to have a beautiful and enjoyable aquarium which they can build from. My angle is that if a guide can be created that people can follow and help reduce the number of fish killed through mistakes then that's a good thing. I know that people should just go and buy + read more books, but lbr people avoid doing that now with the internet.

When I mentioned testing, I mentioned it because I was fully obsessed with testing when I started, testing every day to see the levels change. If you go onto reddit (which I do sometimes), you will see LOADS of people doing things, convinced that their tank with 6 stems in it is cycled after 2 weeks, and when their fish die they are confused. Test kits are useful, but they aren't tools to make things go faster, they aren't better indicators when beginning that things are ready than time and plant growth is. New people can't read an aquarium as an experienced person can, so they rely on test kits, but they also don't tell the whole story.


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## John q (13 Feb 2021)

Just to be clear @shangman i wasn't having a go at you, on the contrary I actually think this a good idea and would encourage you to do it for ukaps.
😃


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## sparkyweasel (13 Feb 2021)

John q said:


> When starting a tank how do we know when its safe to add fish if we don't at some point test for ammonia?


Without fish waste there shouldn't be any ammonia.
If using substrate that leaches ammonia, follow the maker's recommendations for timing.
If adding ammonia to 'cycle', stop.


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## Andy Pierce (13 Feb 2021)

The bacteria are going to be the most bomb-proof things in the tank.  There's nothing you can do (other than adding antibiotics) that will negatively affect the bacteria without first killing everything else.  You don't have to worry about the health of the bacteria and that includes most definitely no need to try to feed them ammonia.


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## John q (13 Feb 2021)

sparkyweasel said:


> Without fish waste there shouldn't be any ammonia.
> If using substrate that leaches ammonia, follow the maker's recommendations for timing.
> If adding ammonia to 'cycle', stop.


Ok fair point and to be clear I'm not advocating adding ammonia although I have done it in the past.

Regards substrate and purely to play devils advocate ~ I'm using ADA power sand and the makers recomendation is to examine water quality with something called a NH4 pack checker before adding live stock.


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## dw1305 (13 Feb 2021)

Hi all,


John q said:


> In terms of planted tanks the holy grail would be to start with a high plant mass and ideally some fast growing stem plants


Yes, <"lots of plants are a prerequisite">. <"Floating plants are best">, because they have access to aerial CO2.  Emergent plants would be even better, but more problematic for most people.


John q said:


> but lots of us do it in secrecy, fearing ridicule if the secret ever gets out.


<"We honestly aren't anti-testing">, the issue is with the accuracy of the testing, not the principle. I would really <"like to know what the water parameters in my tank are">, but if some-one tells me they have "no nitrate", but their plants grow like mad, <"then I know what I trust">.


John q said:


> how do we know when its safe to add fish if we don't at some point test for ammonia?


Just let the plants grow in, <"plant/microbe nitrification"> is much more efficient than "microbe only". I appreciate that it requires a leap of faith, but it honestly is true.


John q said:


> Regards bacteria survival without ammonia it probably depends on which scientific paper you read.


It does, but since we had DNA libraries it has been demonstrated that <"the "traditional"  bacteria">, that we thought were responsible for nitrification, and require high ammonia loadings and pH <"don't actually occur in aquarium filters">.  Have a look at <"Bacteria in a bottle">, if you want <"a scientific paper"> to read <"Bagchi _et al _(2014)"> is a reasonably accessible read for non-scientists.

cheers Darrel


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## dw1305 (13 Feb 2021)

Hi all, 



jameson_uk said:


> I know plants play into this as I guess in a heavily planted tank the ammonia rarely makes it to nitrification and is consumed by the plants before then. How would this differ in a non planted tank?


I never answered this bit, my guess is that you are right and the plants mop up most of the ammonia before it makes it into microbial nitrification. In a non-planted tank you have a few other variables that become more important. 

The first is the level of dissolved oxygen, if you <"can get enough oxygen into the water"> you can potentially microbially oxidise a much larger amount of ammonia. Some types of filter (particularly "wet and dry" trickle filters) are more effective at maintaining oxygenation.



dw1305 said:


> The prime metric in nitrification isn't actually the ammonia concentration, it is the dissolved oxygen level. As you have water with greater amounts of organic pollution its Biochemical Oxygen Demand (BOD) increases, BOD values range from clean water at below 5 mg/l dissolved oxygen up to about 600 mg/L in raw sewage. Water is fully saturated with oxygen at about 10 mg/L, so you can see that you would need to continually add oxygen for nitrification to occur. Sewage works do this via the <"Activated Sludge"> process (below).



The next is pH, if you have pH below pH7 then the TAN remains ionized as ammonium (NH4+) and relatively non-toxic. You would still have issues with subsequent higher levels of nitrite (NO2-)
The next is the nature of the biofilm, if you had a filter medium, like <"floating cell media">, or a fluidised bed system, you have more likelihood of maintaining an effective biofilm for nitrification. 
cheers Darrel


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## sparkyweasel (13 Feb 2021)

John q said:


> something called a NH4 pack checker


I don't know why they call it a 'pack checker' but it seems to be ADA's version of an ammonia test. 5 tests for 11.90 Euros at;
ADA
I wonder if it's any better than, eg API's kit, 130 tests for £8.18 at;
API


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## Hufsa (13 Feb 2021)

Maybe it gives you an overwhelming sense of superiority as you use it 
Otherwise I would bet money its very similar to any other kind of ammonia test..


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## John q (13 Feb 2021)

Thanks Sparkyweasel, thats not something I'll be buying any time soon.


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## jaypeecee (14 Feb 2021)

John q said:


> We should also consider the elephant in the room that is TESTING! We all know these kits aren't accurate but lots of us do it in secrecy, fearing ridicule if the secret ever gets out. When starting a tank how do we know when its safe to add fish if we don't at some point test for ammonia?


Hi @John q 

Firstly, I admire you for raising this point. Everyone should feel able to do what they believe to be correct. Over time, their views may change. If people can back up their alternative viewpoint with a good reasoned argument, then others are more likely to listen. I'm reminded of a TV programme a few years ago in which Harry Enfield portrayed a character who used to go around telling everyone "You don't want to do it like that".  I am sometimes nervous about mentioning test kits on some sites. Indeed, that applies here on UKAPS. But, I have a scientific background and if someone can explain why I shouldn't use this or that test kit, I'll listen. It is wrong to tar all test kits with the same brush, in my opinion. I use a lot of test kits and I wouldn't be without them.

JPC


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## jaypeecee (14 Feb 2021)

sparkyweasel said:


> If the ammonia creeps up again the BB will enjoy a population explosion. Some bacteria can double their numbers in 20 minues if there is sufficient food.


Hi @sparkyweasel 

Whilst it's true that _heterotrophic_ bacteria multiply like rabbits, it is my understanding that _autotrophic_ nitrifying bacteria reproduce slowly. We're talking 15 - 20 hours to double the population.

JPC


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## jaypeecee (14 Feb 2021)

shangman said:


> ...the abstracted scientific process of cycling which confuses beginners and makes them think they can cheat and speed things up by fiddling and doing excessive am/no/na tests.



Hi @shangman 

We obviously beg to differ here. There's no 'cheating' involved and I know from my experience on A N Other forum that many beginners welcome the use of bacterial additives and ammonia to 'condition' their new tanks. And it can substantially speed up the maturation of a tank. But, I do agree that the word 'cycling' is somewhat misleading.

JPC


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## jaypeecee (14 Feb 2021)

Hufsa said:


> Otherwise I would bet money its very similar to any other kind of ammonia test..


Hi @Hufsa 

As I understand it, most ammonia test kits use the salicylate method. So that possibly limits the number of variants of test kits.

JPC


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## jaypeecee (14 Feb 2021)

sparkyweasel said:


> I don't know why they call it a 'pack checker'


Hi @sparkyweasel 

Do they also produce a six-pack checker?



JPC


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## dw1305 (14 Feb 2021)

Hi all, 


jaypeecee said:


> It is wrong to tar all test kits with the same brush, in my opinion. I use a lot of test kits and I wouldn't be without them.


That is the real point, I don't think we are tarring them all with the same brush. I've always advised people to get water parameters from their water company, you can trust them because the water company <"has a dedicated lab."> with analytical equipment and trained staff who can use it. 

The there is the person doing the testing, @jaypeecee, @Zeus., @alto, @reefkeeper1 etc. are scientists and understand <"the scientific method"> etc. Familiarity with standard curves and serial dilutions is likely to stand you in good stead in water testing.

Then there are the tests, some parameters are easier to test for than others, <"a low range PO4--- test"> is going to give you accurate results if you follow the instructions, any nitrate test is going to be more problematic. 


jaypeecee said:


> it is my understanding that _autotrophic_ nitrifying bacteria reproduce slowly.


We just don't know. We can actually ignore the bacteria that those results were based on, because they don't occur in aquarium filters and were just the bacteria that were:

isolated from sewage sludge and 
that we could culture _in vitro_. 
We don't know about the <"diversity of nitrifying micro-organisms that do occur in filters">, because we can't/haven't cultured them and they were found <"using DNA libraries and PCR">. I'm risk adverse, but I would be willing to bet that slow growth rate isn't a universal factor in nitrifying organisms, for the reasons given in the <"one legged Irishman">.  

cheers Darrel


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## jaypeecee (14 Feb 2021)

dw1305 said:


> We can actually ignore the bacteria that those results were based on, because they don't occur in aquarium filters...



Hi @dw1305

The point that I was making was the different reproduction rate of _heterotrophic_ and _autotrophic_ bacteria in aquaria, not the exact species of bacteria. But, I can see that there is an interesting topic for discussion here. As our filters trap organic waste, both types of bacteria are presumably at work inside our filters. What are the implications of this? Should we 'investigate' this further in a new thread?

JPC


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## John q (14 Feb 2021)

Thanks jaypeecee.



jaypeecee said:


> Firstly, I admire you for raising this point. Everyone should feel able to do what they believe to be correct. Over time, their views may change.


Well I haven't been on the forum long and I'm quite thick skinned so was simply saying what I believe to be true.

I've kept fish on and off for over 30 yrs and its been ingrained into my psychology to test and test again. Coming over to planted tanks as been somewhat of a watershed and educational at the same time.
I agree in the main that testing isn't needed per se, but I still think there are times when not to test simply because someone on a forum says so is fool hardy.


Whilst I'm having a rant I'd like to make a comment about adding ammonia to aid cycling a tank. It's something I've done in the past and to me it was better than doing a fish in cycle, which is how we did it years ago ~ and now we have the silent cycle, which it seems is another progression.

What annoys me is how people are quick to jump all over the mere thought of adding half a dozen drops of ammonia to a tank but don't even raise an eyebrow when somebody dumps 10kg of ammonium ladend substrate into it.



dw1305 said:


> Then there are the tests, some parameters are easier to test for than others, <"a low range PO4--- test"> is going to give you accurate results if you follow the instructions



That's interesting darrel, when I set the tank up in September I got a PO4 test kit and for a few weeks obsessed about the high levels, I eventually tested the tap water and got a reading of 2ppm so ditched the kit assuming it was inaccurate.

By the way thanks for steering me toward that AOA paper.


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## jaypeecee (14 Feb 2021)

John q said:


> I agree in the main that testing isn't needed per se...


Hi @John q 

Great to hear back from you! BTW, I must have been otherwise engaged when you first arrived on board HMS UKAPS! So, a somewhat belated welcome from me.

I'm afraid I subscribe to Lord Kelvin's statement that if you measure it, you can manage it (or words to that effect). So, I like to have some figures to toss around. I feel naked otherwise and that's not a pretty sight! So, I test. I'll give you a recent example. Growth of some floating plants recently was suffering. It turned out that the tank water was very deficient in phosphorus. Had I not tested for phosphate, I would still be trying to guess the cause.

JPC


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## dw1305 (14 Feb 2021)

Hi all,


jaypeecee said:


> reproduction rate of _heterotrophic_ and _autotrophic_ bacteria in aquaria, not the exact species of bacteria.


My guess is that autotrophic microorganisms mainly reproduce more slowly then heterotrophic ones, but we don't actually know. <"What do know"> is that most of the ammonia oxidising organisms that we are interested in are Archaea, and that of the bacteria, _Nitrospira _genus contains some species that are canonical nitrite (NO2-) oxidisers and some that are COMAMMOX organisms that directly oxidise ammonia (NH3) to nitrate (NO3-).


John q said:


> I've kept fish on and off for over 30 yrs and its been ingrained into my psychology to test and test again. Coming over to planted tanks as been somewhat of a watershed and educational at the same time.


I think the real difference is that the last thirty years have seen <"huge advances in science">, which on the whole haven't <"trickled down to forums"> or LFS. Personally what has made the most difference to me has been more of an understanding of <"probability and risk">.

If there was a meter or test kit that you could dip into your aquarium and it would tell you all about the condition of the water <"I would unreservedly recommend it">. Again I would guess that at some point we might get nearer to that, until then <"I'm going to stick with best guess">.

cheers Darrel


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## jaypeecee (14 Feb 2021)

dw1305 said:


> If there was a meter or test kit that you could dip into your aquarium and it would tell you all about the condition of the water <"I would unreservedly recommend it">. Again I would guess that at some point we might get nearer to that, until then <"I'm going to stick with best guess">.


Hi @dw1305 

As I've said before, 'sticking with best guess' works for you, Darrel, because of your years of experience as a botanist working with plants. But, put yourself in my shoes working with transistors, resistors, capacitors, etc. and I'm in danger of trying to work out where to connect the battery to make my plants grow better!

On a more serious note, I think an ORP meter is one of the best investments I've ever made for checking the overall health of an aquarium.

JPC


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## dw1305 (14 Feb 2021)

Hi all, 


jaypeecee said:


> 'sticking with best guess' works for you, Darrel, because of your years of experience as a botanist working with plants.


I'm not trying to obscure the fact that it is an advantage, and I'm still better with plants <"than I am with fish">, having said that a lot of members, who aren't botanists, are a lot better with plants than I am. 

I think that we have made a differentiation between <"black and white scenarios">, mainly in <"inorganic chemistry"> and more complex ecological interactions.


dw1305 said:


> .......... I'm a pretty shoddy fish and plant keeper,and I like grown in jungles because they are <"pretty robust and stable">. More skilled aquarists can get manage tanks with a much lower plant mass.





jaypeecee said:


> But, put yourself in my shoes working with transistors..........


I understand that if your scientist working with immutable physical laws then a <"shades of grey"> world is a more difficult concept. To quote <"Lord Kelvin"> 


> ........ _In science there is only physics; all the rest is stamp collecting_..........


but I think that he underestimates stamp collecting.

cheers Darrel


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## sparkyweasel (15 Feb 2021)

jaypeecee said:


> Hi @sparkyweasel
> 
> Whilst it's true that _heterotrophic_ bacteria multiply like rabbits, it is my understanding that _autotrophic_ nitrifying bacteria reproduce slowly. We're talking 15 - 20 hours to double the population.
> 
> JPC


Quite right. But we may have heterotrophic nitrifying bacteria. Once again it's annoying that we don't have much idea of what species we have or are likely to have.
Heterotrophic nitrifying bacteria can be found in marine and waste water environments, I haven't (yet) been able to find reproduction rates for these.
"Highlights
_Vibrio_ sp. Y1-5 exhibited efficient nitrate and ammonium removal in the single aerobic heterotrophic condition."​*Link*
"domestic wastewater using _Bacillus cereus_ GS-5 strain exhibiting heterotrophic nitrification"
Link

On a lighter note, 'breeding like rabbits' always reminds me of a lady who brought a rabbit into the pet hospital where I was working as she (rabbit, not owner) was getting fat. She thought she was feeding her properly, and her other rabbits were fine. We could hardly keep straight faces when she said "and she can't be pregnant because she has only been in with male two or three times."


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## dw1305 (16 Feb 2021)

Hi all,


sparkyweasel said:


> ....... But we may have heterotrophic nitrifying bacteria. Once again it's annoying that we don't have much idea of what species we have or are likely to have.


My guess is that  there are a huge diversity of novel ammonia oxidising organisms (AOA and AOB)  that we haven't found yet and that the microbial assemblage will be very fine tuned, over time, <"to the conditions in the tank/filter">. 

This paper <"Sakoula, D., Koch, H., Frank, J. _et al_. Enrichment and physiological characterization of a novel comammox _Nitrospira_ indicates ammonium inhibition of complete nitrification"> definitely suggests that, and reinforces the idea that initial <"high ammonia loadings"> ("traditional ammonia base cycling") may slow the development of that stable, fine-tuned, assemblage.


> ......_.novel comammox species, tentatively named “Candidatus Nitrospira kreftii”, and performed a detailed genomic and physiological characterization. The complete genome of “Ca. N. kreftii” allowed reconstruction of its basic metabolic traits. Similar to Nitrospira inopinata, the enrichment culture exhibited a very high ammonia affinity (Km(app)_NH3 ≈ 0.040 ± 0.01 µM), but a higher nitrite affinity (Km(app)_NO2- = 12.5 ± 4.0 µM), indicating an adaptation to highly oligotrophic environments. Furthermore, we observed partial inhibition of ammonia oxidation at ammonium concentrations as low as 25 µM. This inhibition of “Ca. N. kreftii” indicates that differences in ammonium tolerance rather than affinity could potentially be a niche determining factor for different comammox Nitrospira._


This one is from <"Heise, J., Müller, H., Probst, A.J. et al. Ammonium Removal in Aquaponics Indicates Participation of Comammox Nitrospira. Curr Microbiol (2021).">


> ....._However, one of the most abundant operational taxonomic units (OTU) was classified as a member of the genus Nitrospira with a relative abundance of 3.8%. For this genus, also genome scaffolds were recovered encoding the only ammonia monooxygenase genes identified in the metagenome. This study indicates that even in highly efficient aquaponic systems, comammox Nitrospira were found to participate in ammonium removal at low steady-state ammonia concentrations........_


This one has recently come my way, but it is 619 pages so I haven't read it all yet. <"Nutrient cycling in aquaponics systems"> 


dw1305 said:


> We don't know about the <"diversity of nitrifying micro-organisms that do occur in filters">, because we can't/haven't cultured them and they were found <"using DNA libraries and PCR">. I'm risk adverse, but I would be willing to bet that slow growth rate isn't a universal factor in nitrifying organisms, for the reasons given in the <"one legged Irishman">.


I'm sticking with that one, remind <"me in ten years time"> and I expect we will have an answer.

cheers Darrel


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## jameson_uk (17 Feb 2021)

This all went a bit Anchorman and escalated quickly...
I have little interest in preaching or trying to convert others and take everything I read with a good pinch of salt (even on here )

Unless I have misunderstood something I still haven't seen anything that would answer the original questions...

Specifically how long would BB last without a food source.   Assuming you took the media out of a canister filter and put it in a bag in a tank that had reasonable oxygenation (ie. some surface agitation) but no bioload (lets assume this is a brand new tank with RO water and no water changes) would the BB survive?   I know all tanks are different and there will be lots of factors to this but was just looking at orders of magnitude, are we talking hours, days, weeks or longer?


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## dw1305 (17 Feb 2021)

Hi all,


jameson_uk said:


> Specifically how long would BB last without a food source. Assuming you took the media out of a canister filter and put it in a bag in a tank that had reasonable oxygenation (ie. some surface agitation) but no bioload (lets assume this is a brand new tank with RO water and no water changes) would the BB survive?


The best we've got is probably  Dr Tim Hovanec's comments in <"Dr Timothy Hovanec's comments about Bacterial supplements">


> ._...... If you look at the forums the overwhelming opinion (at least by the very vocal minority of self-proclaimed experts) is that bacteria can’t live in a bottle, supplements don’t work and it is all just snake oil. I gave up fighting that long ago. This vocal minority seems to think science does not pertain to aquariums but it very much does and biology is complex - that’s the fun part!........................._



cheers Darrel


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