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I Am Showing Nitrates In A Low-tech Planted Tank

8K views 27 replies 4 participants last post by  Chesh 
#1 ·
I am showing 10 ppm of nitrate in my 10 gal. low-tech planted tank. It was zero every week for quite a while. I don't think this is a tap water situation. I do a partial water change once a week of 25%.

I'm trying to figure out why I'm showing some nitrates all of a sudden. I definitely need more plants. I know that aquatic plants can digest ammonia. I'm going to guess that the nitrates are from the friendly bacteria, and whatever ammonia or nitrite gets ingested by plants does not end up as nitrates. Is that right?

I also lowered the photoperiod several weeks ago by one hour to 9 hours (plus 2). Maybe I should put it back up to 10 so that the plants will grow more actively again. That's pretty clear. There are also some other problems going on in this situation: trimmed all my plants at the same time :( got 6 Pristella Tetras; started dosing Flourish Complete and Seachem Tabs.

Thanks a lot for any facts, conjecture, or confirmation. I guess I coulld do a bigger water change every week.

Steven
 
#2 ·
Nitrates are perfectly normal and healthy to have in a fully cycled tank - nothing to worry about, as long as they don't get too high (like 20+ though some fish will be fine with a much higher reading). They are the end-result of the nitrogen cycle. . . ammonia into nitrIte into nitrAte.

May I ask how long your tank has been set up and running? It may be that it is only just finishing it's cycle, and so you haven't seen it appear yet? If you cycle a tank with enough plants, you *might* not see ammonia or nitrite spike, because - as you mentioned - the plants will ingest these toxins. It's really rare for a fully cycled tank to have NO nitrate reading. You have to have very few fish and a LOT of plants for this balance to be created. I've seen you around enough to bet you know about the nitrogen cycle, so I'm guessing this is really just your tank reacting to the addition of 6 new fish. That's quite a bit of bioload added all at once in a 10g tank - my guess is that you maybe had few enough fish for the plants to balance the tank perfectly before, but now you NEED that nitrate to keep up with the increased bioload. Likely it won't go away - and that's okay :)

If this is an older tank, and has enough plants for there to actually be no nitrate reading, it might be a good idea to test your tap water. In the spring, my tap water went from 0ppm to 10ppm in nitrate, because of all the fertilizers people were dumping on their lawns combined with the rain we were getting. This number has since fallen off to 0 again.

This depends on teh plants, of course, but usually trimming them encourages them to grow, and thus take up more nutrients - not the reverse. . . so pruning probably isn't a part of your problem. . . For what it's worth, I'm going with the 6 new fishes! :-D

Hope this helps!
 
#3 ·
Thank you very much. I think the tank has been running for 16.5 weeks. It finished cycling quite a while ago. But thank you for your intelligent commentary. :)

Steven
 
#4 ·
haha! I figured you'd cycled it, already.

99% chance it's just the 6 new fishies! This happened to me, too - my tank was perfectly balanced between very few fish and very many plants for quite some time. Now my nitrate reading sits right at around 7.5. . . still not a bad plan to check the tap. That one threw me for a loop! Now I check my tap every few months juuuuuust to be sure. Stupid city water!

Good luck!
 
#5 · (Edited)
haha! I figured you'd cycled it, already.

99% chance it's just the 6 new fishies! This happened to me, too - my tank was perfectly balanced between very few fish and very many plants for quite some time. Now my nitrate reading sits right at around 7.5. . . still not a bad plan to check the tap. That one threw me for a loop! Now I check my tap every few months just to be sure. Stupid city water!

Good luck!
Thank you! That makes sense, but I wouldn't have thought that six little fish would produce 10 ppm ammonia. I guess it's not too much. But the plants are supposed to pick up *all* of the ammonia. Maybe I just have too much decay action going on. Oh well. I am reading an article that seems tto be saying that plants take in ammonia and nitrite but don't release it until they or a leaf dies, then it re-enters the Nitrogen Cycle. Sounds good to me.

Steven
 
#9 ·
Mika is right - there ARE a million ways to do it right, and and nitrate IS perfectly fine at those levels for the fishies, and will be used as ferts by the plants.

Give it a couple of weeks for things to even out again, and see where your nitrate level is. . .

IF you WANT to TRY to get 0 nitrates, I'd recommend some fast-growing stem plants - they suck that stuff right up! Anacharis might be good to try, FanWort is another that grows very quickly and very well in my tanks... also, true floating plants are the best at soaking up nitrate (and any other toxins) in the water, and there are many of these to choose from :)
 
#12 ·
#13 ·
Looks like you answered your own question there :)

I looked back, and I actually DID incorrectly tell you to look into Walstad at the same time as I told you plants prefer to feed on nitrate - I knew what I meant, and typed it backward, I'm sorry . . I've actually been in some heated debates with older fishkeepers over this topic lately. . .

To actually answer your question. . . um, you're asking the wrong person! Go ask Byron, he knows stuff about stuff! I've actually been actively trying to figure out exactly what makes my little ecosystem work since the day I set it up!

I have a moderately planted tank, I guess - all of my tanks are or are getting there. I've now successfully cycled 4 tanks, fish in, with lots of gorgeous plants and NO toxin spikes. I am firmly convinced that my plants are solely responsible for this. After some time, the nitrate levels slowly start to rise, but stay low - and in the case of my one-time lightly stocked 29g, remained at 0 for quite some time. However. . . even when the nitrate reading in that tank had been at 0 for weeks, I was able to cycle a tank with no plants using a small amount of substrate taken from the 29 - there were slight traces of ammonia and nitrite as things were settling in, but only lightly, and only for the first few days. So I also had enough bacteria, even with a 0 nitrate reading, to seed the new tank very well.

After reading some of Walstead's book (it's big - I need more time!) I had the same questions as you seem to be asking - pretty much I was wondering if I even HAD a cycled tank - or if I just had enough plants to keep things happy in there. These things are kind of important!

From my own (very narrow) range of experiences, I think that in my tanks things are fairly evenly balanced between bacteria and plants. . . which is a good thing. I've run into trouble with both filters AND with plants, and cycled far more tanks than I ought to have - yet my tanks have remained toxin-free. I know for a fact that there is a good amount of bacteria in the filter, but I also know that there is at least as much of it in the tank - regardless of plant-life.

As to who gets the toxic goodies first, I really don't know! Figuring out what exactly is going on in my tank is fascinating to me, but as soon as I feel that I've gained some understanding, I run into conflicting, and seemingly equally scientific explanations for what I just *thought* I had figured out! I'm not very scientific minded, anyway - this stuff (though I LOVE learning about it) makes my eyes go all funny!
 
#14 ·
Checherka (sorry if I misspelled your name - I didn't want to quote your whole post),

Thank you very much for your post. It sounds like you have been very successful with your tanks, and you probably have been doing this for some time. I haven't read Walstead, except in the article I put a link to.

Re my tank, I think I must have done a lot of the right things and not made too many mistakes, with Rhymon87's tutoring and sometimes by accident. Of course, I read a lot too, but Rhymon was the one who helped me the most.

Anyway, this idea of competition for ammonia by bacteria and plants and the issue of why a tank with lots of plants and few ammonia producers doesn't generate nitrates from the Nitrogen cycle. I don't know. It happened to me too. Maybe the answer I put forward in my initial post was wrong, and maybe the plants just take up ammonia faster than the bacteria. I just don't know. But it's good that things are the way they are.

As you can see, I've been trying to figure out how my tank works for a while, I really appreciate this discussion.

Steve
 
#15 ·
#16 ·
heehee, I have only been doing this for 5 months... almost to the day - and I got some bad information on forums and such until I also found someone more experienced to help me through - which is why I'm always very careful to let folks know that I don't necessarily know what I'm talking about. I have 4 tanks right now, and have already shut down and re-started a few - every tank IS different, though the science behind them is the same. I've learned so much over the last few months from my experiences and reading everything I can find (which is often contrary - both online and in books). I'm always happy to talk fish, just don't want to lead anyone in the wrong direction ;)

I don't think that one counter-balances the other, in this case. The snippet of the article you sent doesn't get into all of the details . . .

Nitrification enhanced by filters is essential for protecting fish from toxic ammonia in aquariums without plants.
note the word used - ENHANCED. . . the bacterial filtration is still a part of the working tank - the filters are just providing the non-planted tank with a bit more surface area for the bacteria to colonize. The rest of this bit is as follows:

However, planted aquaria are a whole different ballgame. In fact, plants provide an enormously increased surface area within the aquarium for nitrifying bacteria. Planted areas (as opposed to unplanted areas) in natural habitats (rivers, lakes, etc) have been shown to provide an exponentially increased number of colonization sites for bacteria [9]. You can be sure that every leaf and stem surface in an established aquarium is coated with a layer of nitrifying (and other) bacteria.
Speaking of a natural environment - and the vast amounts of bacteria found there - without filtration, obviously. . .

I have been surprised at how little biological filtration is actually required in my planted aquaria. When I gradually decreased biological filtration by removing the packing media from the canister filters, the fish continued to do well. Finally, years later I took the decisive step and removed the canister and outside filters altogether and just used cheap internal pumps to circulate the water. Fish never missed a beat; the planted tank itself is a filter!
Hmmm? Again?
"I have been surprised at how little biological filtration is actually required in my planted aquaria."
Based on what was said previously, I believe this should have been written as "mechanical filtration" NOT biological, as what has been said before 'proves' that the biological filtration is already in place - even MORE SO in a planted tank with more surface area to colonize, and in nature - where there rarely ever is a detectable nitrate reading.

So. . . looking at the article you posted by Walsted. . .and also what I've seen first-hand in my own tanks, and read elsewhere. . . I think that both the biological filtration, and filtration from the plants occur simultaneously - even in nature. Thought it would be cool to know who gets the benefit of the nutrients first, I suspect that both the plants and the bacteria co-exist and develop simultaneously in the tank. . .

:)
 
#17 ·
Chesherca,

Thank you for the response.

What is really interesting to me is that the normal state of a balanced tank with plants may be zero NO3. At this point the plants may be getting all or almost all of the ammonia in the water, because the ammonia is going along at such a low level that the nitrifying bacteria are inactive, as you must have a certain level of ammonia for them to be actively using it.

The plants hold on to the ammonia and release it when they or leaves die. And so things go on. However, if a new source of ammonia appears that the plants can't handle by themselves, in ride the cavalry of nitrifying bacteria and you start seeing nitrate after a while.

Most of this is weaving together things from articles with a little original thought. It's an interesting theory.

Thank you

Steven
 
#18 ·
At this point the plants may be getting all or almost all of the ammonia in the water, because the ammonia is going along at such a low level that the nitrifying bacteria are inactive, as you must have a certain level of ammonia for them to be actively using it.
I don't know if that's really true, though - because in nature - where there is automatically a balance between low 'stocking' and much plantlife, there is a lot bacteria, and no readable nitrate. Granted, in some bodies of water, this is because the water is constantly changing itself - like in a stream. However. . . this is not the case in all bodies of water. . .

You may be right - I don't honestly know, but I was able to cycle a new tank with substrate and no plants in record time while my tank had the balance of a 0 nitrate reading, so I tend to have the viewpoint that it's there - whether you see it with your test kit or not, the bacteria is there. I'm a water-test junkie with new tanks, I just like to make SURE of what's going on - especially if living fish are concerned. I do water tests on new tanks once a day until I'm quite sure they're stable - and sometimes even more, if I'm feeling nervous. . . I don't know how much of this stuff we can actually figure out only with the test kit, though. You should start a thread, I'm sure there are others out there who have a far clearer picture than we noobs do ;-)

Really neat stuff, either way!
 
#19 ·
I depends on lots of factors. Also plants won't touch nitrite far as I know, ammonia/ammonium is the most preferred form and nitrate is second. Nitrate must be converted back into ammonia/ammonium within the plant before it can be used. Many other factors are also responsible, from amount of current to levels of non-nitrogen nutrients. Also not all bodies of natural water have no readable nitrate. Remember a natural ecosystem is much more open then an aquarium and often rain events carry in runoff water that has picked up considerable nutrients from soil above the water line.

I run most my tanks following EI dosing principles. Preferably nitrate never hits 0, as nitrogen is a macro nutrient for plants. EI recommends 20ppm though and I dose nitrates to achieve that.

I have a few tanks that operate similar to the walstead method. AKA unfiltered with just regular water changes. My 20 high has been unfiltered and has 0 water movement all week and its doing fine.
 
#21 ·
I think that water movement is very important to the health of plants and bacteria. It brings their food needed for energy and allows more oxygen and carbon dioxide from the surface to other places in the tank, enabling greater dissolved oxygen and CO2 in the tank. <rant off>

Also, you can trust me when I say I have read that the preferences for nitrogen for plants is ammonia, nitrite, then nitrate, if that makes any difference. When there is no more ammonia present, nitrite gets a chance and so on.

My idea, or the way I'm putting things together, is that when plants can't assimilate any more ammonia, or don't do it fast enough, the nitrifying bacteria go to work and you get nitrate. Otherwise, you don't. I think it means that there is an imbalance in the plant-fish-bacteria relationships. I wonder what happens to the nitrifying bacteria when there is 0 nitrates?

Thanks for your reply, and I'm glad we could exchange ideas.

Steven
 
#23 ·
Well I guess everyone has a right to their own methods, and people are looking for something that works.

Thanks for taking the time to reply.

Steven
 
#24 ·
Mika, I miss you! I need to stop into chat again soon. . . It's always good to hear your take on things - I just love your way. (but I'm sure you know that by now :razz:)

Steven. . . there are two sides to every coin, and our world is made up of many very different types of water - and all of these support their own equally unique life-forms. Some are oxygen-rich, others deprived - all have fish and plants that thrive there. In a community aquarium, we're kind of playing a mix-and-match game, and what works for one may fail utterly for another. Mika has a very distinct and unique way of going about things compared to many others that you'll run into here. But it WORKS for her, and can't be denied. I think that . . . in many ways. . . fishkeeping is part science, partly intuition/common sense, and partly an art-form. That's all very random and whimsical sounding, but. . .

when plants can't assimilate any more ammonia, or don't do it fast enough, the nitrifying bacteria go to work and you get nitrate. Otherwise, you don't. I think it means that there is an imbalance in the plant-fish-bacteria relationships. I wonder what happens to the nitrifying bacteria when there is 0 nitrates?
I've been wondering the same thing. . . perhaps they do shift work? If the plants are only actively processing toxins through photosynthesis during 'daylight' hours, wouldn't said toxins build up overnight? Do fish pee in their sleep?! LOL! I have lots of nocturnal creatures, from loaches to frogs, and the snails that never seem to stop, plus decay from dying plants, fish waste, and decaying food particles is a continuous process. Perhaps the bacteria absorbs enough nutrients during the times when the plants are 'sleeping' to keep the balance perfectly (assuming that you are correct in your assumption that the plants out-compete the bacteria for nutrients). I've never seen an ammonia spike in the evening hours - but I've also never seen a nitrate spike in the early morning. Plants may or may not prefer to use nitrate as an energy source, but they can and they do if it becomes necessary. Assuming that the precious ammonia is taken up as soon as it enters the tank, it would make perfect sense that the plants are then forced to take in the only nutrient that is left to them - nitrate - in addition to any fresh ammonia that they are able to get (in competition with the bacteria) during the day and photosynthesis.

It's too late again for me to be responding. I hope that made *SOME* sense! Really, there is no way for either of us to honestly know - we're the blind leading the blind, and we need more trustworthy scientific indisputable hard evidence to really know for sure.

Debate and curiosity are always good things in my book - but I DO want answers that are a bit more solid than internet readings and random thoughts. . . *shrug*
 
#25 ·
I think you have the right to accept or not accept any information you want to. And that goes for me too. I agree that there is more than one answer to any question and of course, ideas must be tested by experimentation, observation, or consensus before they are accepted as fact.

You made a good point about nitrifying bacteria working nights as well as days, when plants are (as far as I know) just respirng at night. This means I really don't know how it works and I have to do some more reading, whether books or through Google searches to figure out how plants outperform nitrifying bacteria in assimilating ammonia and how nitrifying bacteria deal in that situation. I guess I didn't think it through enough. But it's nice to work things out with other people in a forum environment.

Steven
 
#27 · (Edited)
Interesting thread, here are my observations on the topic.

This is a scientific hobby, like it or not, and science is the key to success. All life forms have the ability to adapt; this is after all the basis of life on earth--evolution. We wouldn't be here discussing this if life had not evolved as it has. So it should come as no surprise that fish and plants can adapt--somewhat.

All species are designed to function in a specific environment. As that environment changes, so must the species if they are to continue.

Aquarium plants can manage in varying conditions. It is next to impossible for anyone but a trained botanist to determine the extent to which this or that environment (or factors within the environment) are more or less beneficial to a plant. I have maintained the same plant species under varying conditions, not experimentally but just practically, and while the plants continued to grow I was able to notice varying responses from the plants, but certainly not to the extent of pinning it down with numbers.

The scientific data in the articles previously linked speak for themselves. As science advances in its understanding of life, changes are bound to occur in how we approach aquarium maintenance. Sometimes this may be significant, other times almost immaterial. It used to be thought that aquatic plants like their terrestrial counterparts, used nitrates as their source of nitrogen; we now know for a fact that this is not the case for the majority of species. But no one is going to pump ammonia/ammonium into their aquarium if fish are present. And in any case, the evidence suggests that this would have minimal impact on growth since the plants generally have sufficient ammonia/ammonium present for their needs in a natural setup. High-tech is another aspect.

Nitrifying bacteria will exist in any fish aquarium, plants or no plants. They will be less with more plants, and the point is that with plants in a natural method tank we do not want to encourage nitrification since this is clearly in competition with plants, and we want the best conditions for the best results. Whatever the method, things must be in balance.

Byron.
 
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