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Discussion Starter · #1 ·
I'm trying to find a balance between flora, fauna, and filtration, and was wondering if the bacteria in a bio-filter will deplete any of the other same nutrients that plants utilize, or is it just ammonia/nitrites/nitrates that bacteria use?

I wouldn't doubt that certain bacteria might have metabolic processes somewhat similar to plants, apart from the the photosynthesis aspect, but I haven't seen anything about this anywhere.
 

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Bacteria will consume Ammonia/Nitrites, but they will not consume Nitrates. That's one of the big reasons why you have to do water changes in unplanted tanks. The bacteria will consumer the Nitrite and produce Nitrate as a waste product. If all you do is top off your tank, eventually the Nitrate gets to dangerous levels.
 

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Discussion Starter · #5 ·
I wasn't quite sure what to take from these links. Aren't there hundreds of different species of bacteria each fulfilling different ecological niches? Walstad describes in her book that just your standard biofilm is a complex woven matrix of many species and layers.

And I'm worried that my overfiltration approach is making my life more difficult by potentially depleting not only the nitrogen but other necessary nutrients as well.
 

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Discussion Starter · #6 ·
Bacteria will consume Ammonia/Nitrites, but they will not consume Nitrates. That's one of the big reasons why you have to do water changes in unplanted tanks. The bacteria will consumer the Nitrite and produce Nitrate as a waste product. If all you do is top off your tank, eventually the Nitrate gets to dangerous levels.
That is unless you're using a denitrifying medium, as I am. Look up Seachem Matrix. I took most of mine out of my filter though as I just realized I had almost zero nitrates. Not to mention that plants can deplete nitrates as well, but I'm not yet sure which was the culprit in my case.
 

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I wasn't quite sure what to take from these links. Aren't there hundreds of different species of bacteria each fulfilling different ecological niches? Walstad describes in her book that just your standard biofilm is a complex woven matrix of many species and layers.

And I'm worried that my overfiltration approach is making my life more difficult by potentially depleting not only the nitrogen but other necessary nutrients as well.
This is a common misconception among cichlid keepers.

Regardless of how MUCH filtration you have, your bacteria level is 100% dependent on your waste production. If you have x ppm of ammonia and y amount of filtration/gph/area, the amount of bacteria present is only relevant to X.

While some medias might be easier for bacteria to populate, or might congregate more bacteria in one spot, no filtration will give you More or less bacteria. As a matter of fact, bacteria do not care what they are attached to and they will attach to your filter floss just as quick as your bio rings or bioballs.

You could run enough filtration for 15000 gallons on your tank and it will have no effect on bacteria or the end result. The main reason TOO LITTLE filtration is a problem is water polishing and solid waste removal, combined with too little flow/oxygenation.

I'm not sure how it came to be that people think that more surface area=more beneficial bacteria... but it just isn't true. There is only as much bacteria as there is food. No more. No less. The amount of flow/filtration has nothing to do with this, as the bacteria would just colonize other areas.
 

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Discussion Starter · #8 ·
I agree with this generally, although that's not the case for everyone. And if any aquarists have ammonia or nitrites present to any degree in their tanks (as many do) then that means they still have insufficient surface area in their biofilter and/or have insufficient plants. (Or they've taken improper care of their bio-media and killed the bacteria in it by washing it in tap water).

The potential problem there is whether my filtration is out-competing my plants for nitrogen as well as other nutrients. I am seeing some sort of deficiency at the moment though I haven't yet pinpointed which one but am working on trying to at least increase my nitrate levels for the moment.
 

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I agree with this generally, although that's not the case for everyone. And if any aquarists have ammonia or nitrites present to any degree in their tanks (as many do) then that means they still have insufficient surface area in their biofilter and/or have insufficient plants. (Or they've taken improper care of their bio-media and killed the bacteria in it by washing it in tap water).

The potential problem there is whether my filtration is out-competing my plants for nitrogen as well as other nutrients. I am seeing some sort of deficiency at the moment though I haven't yet pinpointed which one but am working on trying to at least increase my nitrate levels for the moment.
This means you need to ADD nitrogen. You biofilter isn't out competing anything. Biofilters do not consume nitrate. They convert ammonia to nitrite to nitrate. Plants can consume all three. What is happening is your plant mass is higher than your nutrient supply.

Without a single doubt in my mind there is no way, shape or form a biofilter can out compete anything. The plants still use the final product.

This is common in planted tanks and is basically the only reason I'm in business. We put a high mass of plants in even a low tech tank and the plant does not produce enough nutrients. This means we have to add npk/micros.

Again, it has absolutely nothing to do with your biofilter. If you step back you'll see that it isn't actually relevant.
 

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Have you added something extra to the seachem matrix that you believe contains denitrifying bacteria? If not, it contains the same bacteria as any other biological filter. Their ad copy about its shape being perfect for denitrifying bacteria is bunk. There are special filter additives that can absorb nitrates, and some saltwater tanks run nitrate reactors to convert their nitrate into nitrogen, but it's not something that happens on its own.

Excepting the case in which you have added something to the filter, I would strongly suggest the plants in the tank as the source of your zero nitrates. They love the stuff.
 

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Discussion Starter · #11 ·
I may very well need to add nitrogen, but I'll see if cutting down on my biofilter media makes a difference first and brings up my nitrate levels first. Do you by the way ship to the UK?

My current tank is a bit of a trial, in that it has high plant mass, high fish mass, and serios overfiltration, (that size of canister filter happened to be cheapest on Ebay that day), and I'd expected the high fish mass to produce more nitrates than the plants could utilize, but previously I haven't tested accurately to tell.

Take a look into anaeobic bio-filtration, which modern reefkeeping is predicated on through the use of live rock. Anerobic bacteria within a microporous medium naturally break down nitrates, but you don't need me to prove that to you.
 

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I may very well need to add nitrogen, but I'll see if cutting down on my biofilter media makes a difference first and brings up my nitrate levels first. Do you by the way ship to the UK?

My current tank is a bit of a trial, in that it has high plant mass, high fish mass, and serios overfiltration, (that size of canister filter happened to be cheapest on Ebay that day), and I'd expected the high fish mass to produce more nitrates than the plants could utilize, but previously I haven't tested accurately to tell.

Take a look into anaeobic bio-filtration, which modern reefkeeping is predicated on through the use of live rock. Anerobic bacteria within a microporous medium naturally break down nitrates, but you don't need me to prove that to you.
I do ship to the UK. Rootmedic.net will auto calculate shipping for that.

Live rock in reef aquariums has nothing to do with bio filtration in freshwater aquariums. You might not have tested it, but I and a bazillion others have.

High plant mass consumes more nitrates(and phosphorus and potassium) than fish put in. It might not be what you think, but it is true.

If you've magically formed denitrifying bacteria in your filter, take it out and sell it. It is rarely than diamonds and platinum.

See this:
http://freshwatercichlids.com/do-it-yourself-coil-denitrator

The amount of work and the return are not worth it, and you can't get these results in a normal filter.

REGARDLESS of the amount of bio filtration you have, it doesn't matter. All it is, is surface area for bacteria to grown. Having too much surface area does not mean that you have more bacteria. Bacteria requires food and it consumes ammonia for food. It turns ammonia to nitrite, which is then in turn converted to nitrate. Plants eat nitrate faster than any of the other nutrients, and in a planted tank, ZERO NITRATE IS ALWAYS FROM PLANTS. ALWAYS. ALWAYS. ALWAYS. Bacteria will only replicate at the rate in which their food supplies them. End of discussion.


ALWAYS.

This just means you need to supplement your plants, turn down your lights, or have less plants. I don't care what you do to your filter, you'll never change this.

I will bet you a years worth of RootMedic, that your biofiltration has nothing to do with this.

Hell, I'll bet you RootMedic. The WHOLE company. I'm that sure. Your plants are consuming the nitrogen. That is what they do.
 

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The only way you will get bacteria to convert nitrate into N2 gas is if the bacteria are in an anaerobic environment. The denitrifying bacteria are facultative, meaning they survive in either aerobic or anaerobic conditions. In environments with dissolved oxygen (like our tanks) they use the free oxygen to process their food. In anaerobic environments where there is no free dissolved oxygen, the bacteria will strip the oxygen from nitrate (NO3) molecules, producing N2 gas. Other by products of anaerobic environments are methane gas, hydrogen sulfide and dead fish.
 

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Discussion Starter · #17 ·
Thanks everyone, and so we seem to once more have a series of mixed opinions, in this case on whether or not bacteria consume other nutrients in addition to nitrogen, (as I personally had suspected they do). Unfortunate if we don't have a definitive answer though. Rather varied views on denitrification as well...

In any case, many aquarists run successful Natural Planted Tanks with little or no filtration, and no dosing. I don't have a soil base in my tank so mine isn't exactly that approach as plants in an NPT tank obviously are able to obtain a lot of nitrogen from the soil. But the NPT tanks are generally run with low bioloads, and the fish+food nevertheless seem to be accumulating sufficient nutrients to supply the plants as necessary. I'm personally testing whether a similar approach works with higher bioloads plus generous filtration, and I'm now reducing my filter media to try and see if I can get nitrogen levels to slightly rise and help see how much nitrogen my plants are consuming.

To hypothetically consider this issue another way, in say an average non-soil fully planted medium light tank, how much would you need to increase your fish load and feeding before your fauna would be producing the maximum amount of nitrogen which your plants are able to consume and you thus aren't having to dose nitrates to keep from limiting your plants? (Not that trying to maintain that exact delicate balance would be good practice or something you'd want to try, but I though it would be helpful to understand this). Is it 100% aqadvisor fish stocking density? 150%? 200%?

And would a tank with massive bio-filtration but no plants at all still end up having the same water quality as a fully planted tank, because the bacteria in the bio-filtration would end up depleting all the other organic byproducts including phosphates, trace nutrients introduced in food, etc?

I read the articles on autotrophic and heterotrophic bacteria, which I learned a bit from and confirmed some of my prior understanding. I don't arrive at quite the same conclusion as the author there however. I don't see why the author is quite so fearful of heterotrophic bacteria, which are a necessary part of our tank's ecology and which will themselves be limited by their energy sources. Therefore it seems in any tank with sufficient filtration, (though many don't have sufficient filtration), the heterotrophic bacteria will naturally achieve the correct balance with autotrophic bacteria so long as they're not each limited by available surface areas to colonize. And in a planted tank you're essentially depending upon the plants to fill the role of consuming the same nitrogen which autotrophic bacteria would be consuming instead. He is writing in relation to keeping Oscars which is of course, ahem, rather a different kettle of fish than what we're dealing with.
 

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Thanks everyone, and so we seem to once more have a series of mixed opinions, in this case on whether or not bacteria consume other nutrients in addition to nitrogen, (as I personally had suspected they do). Unfortunate if we don't have a definitive answer though. Rather varied views on denitrification as well...

In any case, many aquarists run successful Natural Planted Tanks with little or no filtration, and no dosing. I don't have a soil base in my tank so mine isn't exactly that approach as plants in an NPT tank obviously are able to obtain a lot of nitrogen from the soil. But the NPT tanks are generally run with low bioloads, and the fish+food nevertheless seem to be accumulating sufficient nutrients to supply the plants as necessary. I'm personally testing whether a similar approach works with higher bioloads plus generous filtration, and I'm now reducing my filter media to try and see if I can get nitrogen levels to slightly rise and help see how much nitrogen my plants are consuming.

To hypothetically consider this issue another way, in say an average non-soil fully planted medium light tank, how much would you need to increase your fish load and feeding before your fauna would be producing the maximum amount of nitrogen which your plants are able to consume and you thus aren't having to dose nitrates to keep from limiting your plants? (Not that trying to maintain that exact delicate balance would be good practice or something you'd want to try, but I though it would be helpful to understand this). Is it 100% aqadvisor fish stocking density? 150%? 200%?

And would a tank with massive bio-filtration but no plants at all still end up having the same water quality as a fully planted tank, because the bacteria in the bio-filtration would end up depleting all the other organic byproducts including phosphates, trace nutrients introduced in food, etc?

I read the articles on autotrophic and heterotrophic bacteria, which I learned a bit from and confirmed some of my prior understanding. I don't arrive at quite the same conclusion as the author there however. I don't see why the author is quite so fearful of heterotrophic bacteria, which are a necessary part of our tank's ecology and which will themselves be limited by their energy sources. Therefore it seems in any tank with sufficient filtration, (though many don't have sufficient filtration), the heterotrophic bacteria will naturally achieve the correct balance with autotrophic bacteria so long as they're not each limited by available surface areas to colonize. And in a planted tank you're essentially depending upon the plants to fill the role of consuming the same nitrogen which autotrophic bacteria would be consuming instead. He is writing in relation to keeping Oscars which is of course, ahem, rather a different kettle of fish than what we're dealing with.
I didn't read much of this.

But I can give you a definitive answer that bacteria can convert tons of things into tons of things.
Do those bacteria exsist in your fish tank? I don't know.
Do they absorb nutrients that your plants need? Your plants can use ammonia and nitrite, bacteria eat that stuff, but there are again, probably not bacteria in your tank turning nitrate into anything else.
And NO, your typical bio-filtration, which you are assumed to have when the tank is cycled, does not absorb phosphate, pottasium etc, etc.
They probably do in minute quantities just as simple requirements for cell metabolism, but in order to need enough of certain trace elements to reduce tank values to 0 the food source for them would have to be HUGE, and thats not gonna happen!

So no, your bacteria have nothing to do with your nutrients other than absorbing ammo and nitrite which plants love.
But yes, bacteria in general are capable of eating almost anything, and turning it into anything, but its going to be on a species to species basis.
No one species can eat more than a few things, and most can't really eat more than one. (eat meaning, element A is its food source, and element B is its poo, aka Ammonia is food, Nitrite is poo.)
 

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The only way you will get bacteria to convert nitrate into N2 gas is if the bacteria are in an anaerobic environment. The denitrifying bacteria are facultative, meaning they survive in either aerobic or anaerobic conditions. In environments with dissolved oxygen (like our tanks) they use the free oxygen to process their food. In anaerobic environments where there is no free dissolved oxygen, the bacteria will strip the oxygen from nitrate (NO3) molecules, producing N2 gas. Other by products of anaerobic environments are methane gas, hydrogen sulfide and dead fish.
Yes,, BOD's (biological oxygen demand) is important consideration, especially in sealed canister filter where maint is not performed on regular basis.(monthly in my view)
Bacteria starved of oxygen will not be as healthy a population (anerobic condition).Keeping filter's clean, regularly will help prevent this.
You can remove all biological media (ceramic,matrix,substrat pro,etc) and just use foam pads,floss,sponges,etc and bacteria will colonize these surfaces as well, and water through this media will be a bit less restricted = a bit more flow.(this is good in my view)
Believe there is a big difference between Nitrogen in form of mineral salt KNO3, and Nitrogen levels as result of decaying organic's (food,poop,dead plant material,)
Plant's will use it all, but in unplanted tanks holding fishes,, whether they be cichlid's or other species,the source of nitrate level's from the afore mentioned decaying organic's, depending on how high the level's are,,, are an indication of poor management = possibly sick ,dying fish.
I agree with other's, I would increase KNO3, KH2PO4, before considering removing biological media,or reduce plant mass if improving growth was my aim.
 
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