Reducing Nitrate Without Water Changes

Hey everyone! I'm new to this forum, and I hope it's okay digging up a thread from years ago (if not, sorry in advance). This is literally my first post. The topic seems important to hobbyists and quite misunderstood to many. I think I have some valid comments with regard to aquarium plants and nitrate management, and I hope you find the post useful.

To substantiate my claims, I'm going to add some pictures of the tanks I'm currently running. I have three tanks, all planted, ranging from high light/high tech/high CO2, to low light/low tech/no added CO2. I've had a pretty high success rate with both fish and plants in all tanks. Plants only seem to do poorly if there is an algae outbreak, and the leaves get coated with the stuff. It has really only been an issue for one tank, and honestly its not very bad (I've seen much worse).

It seems universally agreed upon (by experienced and serious aquarists) that adding chemicals to your tank should only be done as a last resort. It seems very convenient, but it should be avoided... and on topic with this thread, it is much more expensive than water changes. Spend that money on some new fish .

In my personal experience, plants have certainly proven themselves effective for nitrate control. They soak up all the bad stuff (it's good to them!) while releasing oxygen that your fish will appreciate. In addition to the benefits to you water parameters, plants make an aquarium look organic and beautiful (sometimes even stunning) when properly placed. One more benefit is that fish love to hide and swim amongst the stems and leaves--it makes them feel more at ease, and plants are even required to coax certain fish into breeding.

As for the comments about needing many plants and few fish in order to keep nitrates down, it is, at least from my experience, false. I have 23 fish and between one and two dozen ghost shrimp in my high-tech 75, and I do almost ZERO WCs! I've occasionally used a plastic pitcher to skim the water's surface, to remove a thin film of tannin seepage (from driftwood). Other than that, I perform an EXTREMELY SMALL (about 5 or 10%) WC My ammonia and nitrite levels always read zero, unless I add several fish at once (then they may reach up to 5ppm). Nitrite levels stay between 5 and 20ppm.

In my low-light/low-tech/no CO2 75, there 18 hardy fish. I have perform water changes a bit more frequently on this (about 10-15% every week) because they're all hard fish, and feed them a ton. on that one, because they're all heavy eaters, and they're all getting fairly large. Nitrates stays a bit higher in this one (20-40ppm) as the plants don't use as much, being a low-light setup. About zero ammo and nitrites.

Finally, my 29 low-tech/light/CO2, has only three fish: two peacock cichlids and a bristlenose plec (currently trying to find good tank mates to add). They aren't huge and don't eat a ton, but I haven't performed a WC in weeks and nitrates stay between 5 and 10ppm. Again, virtually zero ammo and nitrites.


I understand that aquarium plants aren't for everyone. They do require some upkeep (trimming back, re-planting, propagating, etc.) and nutrient dosing isn't free (though it also isn't always necessary). However, they are a great addition if you like the look and dislike massive and frequent WCs. Hope this post is useful!

Hi and welcome to the forum

Wow, there's a lot of misconception in this thread. Where to start....
Faced with high nitrates in my well water due to a 95 acre farmers field across the road, I have waged war against nitrates for years.
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Good tank/filter maintenance and proper feeding goes a long way towards reducing nitrates. Something as simple as sand instead of gravel can make a huge difference. This is because gravel can become a 'nitrate factory' as detritus and uneaten food easily gets down under.
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Fast growing plants, especially floating plants will indirectly reduce nitrates. Although they prefer ammonia as their N2 source, the ammonia they use will not be converted to nitrites, then nitrates by nitrosomonas and nitrospira bacteria, BUT, these must be fast growing plants as many slow growing plants just don't cut it. (So nutrients [aka pollutants] are removed with plant trimmings). The correct plant mass to bio-load is never clear and typically, in the average tank, nitrates will still slowly rise.
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I have used Seachem Matrix and De*Nitrate (a pumice stone) in a filter with a slow flow in order to encourage the culture of anaerobic bacteria to convert nitrates into nitrogen gas. I believe that creating the anaerobic conditions necessary in the highly oxygenated FW environment is very difficult, I was never successful! MarinePure's CerMedia looks promising, but I have yet to try it.
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Products like API's NitraZorb are effective at filtering out nitrates. I use this to pre-filter my well water, It can be recharged many times with salt water. The downside is that when used in pouches in the aquarium filter, it's use life is decreased by detritus. It's unclear if you can reclaim the resin with chlorine bleach.
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It was mentioned in this thread that nitrates, even high nitrates are not harmful to fish. This just couldn't be more wrong. The negative affects of long term exposure to high nitrates is well documented. it reduces the fishes immune system making them more susceptible to illness and disease and reduces their lifespan.
I don't know where some of these ideas come from.
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All said and done, nitrates are just one measure of pollution as there are other negative compounds that result from organic decomposition. Even though plants help to purify water, the easiest and best solution to pollution is dilution. A routine weekly (or even bi-weekly) water change of 50-75% is very beneficial in maintaining the very best "FRESH" water quality.
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@Geigetron343 - Welcome to the forum. However, I question your test results. First, based on my experience, you have insufficient fast growing plants to counter rising tank nitrates. You also indicated (at least in one tank) that you have nitrites and zero nitrates. In the established tank, you would not be able to measure any ammonia or nitrites, but will always have some nitrates. I suspect that your testing is not accurate. If you're using the API FW test kit, I'm thinking that regent #2 is bad, or not shaken enough, or something is off.
Regards, Mike

I came across this thread earlier today, and noticing it was an old thread resurrected didn't really give it much thought at first. But Mike (AbbeysDad) has made some extremely valid points and I've given things another look.

I don't know why some "sources" still try to get aquarists to believe there is really no need or benefit to water changes, or that this or that can somehow make them unnecessary. This is totally false. Absolutely nothing benefits any aquarium as much as regular and substantial partial water changes...assuming it is stocked as most of us stock. Half a dozen tetras in a planted 60 gallon tank might manage without water changes, but not much beyond this.

I have good growths of plants in all my tanks, and all have floating plants. I still change 50% minimum, but more like 65-70% of the tank volume every week, and I would not do otherwise. Nitrate fluctuating are a sure sign of problems, as the water condition should be stable from week to week. This is the great value of water changes, stability. My tanks have 0 to 5 ppm nitrates, and have for many years now. Nitrates are toxic to fish; levels and species can have different reactions, but the bottom line is that nitrate like ammonia and nitrite is toxic.

Byron and Mike are quite correct.

Personal rant

I just do not see why people are reluctant to do regular water changes, I do regular 75% water changes every week, plus I do 50% water changes because Im bored or because well I dont need a reason I just do it. I always have enough pre treated water on hand to do a 50% water change.

And that includes the 100 gallon tank.

My BBG tank gets a 50% water change every 3 days, I wanted BBG's now its my responsibility to provide the best care I can.

And before anybody says anything my BBG's are almost as big as a 7 month old female Betta.

AbbeysDad said:

@Geigetron343 - Welcome to the forum. However, I question your test results. First, based on my experience, you have insufficient fast growing plants to counter rising tank nitrates. You also indicated (at least in one tank) that you have nitrites and zero nitrates. In the established tank, you would not be able to measure any ammonia or nitrites, but will always have some nitrates. I suspect that your testing is not accurate. If you're using the API FW test kit, I'm thinking that regent #2 is bad, or not shaken enough, or something is off.
Regards, Mike

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Thanks for the welcome. Mike, I appreciate the post, but must say you freaked me out a bit. I immediately dropped my botany homework and ran to my LFS to get two new water test kits (spent like 50$, but that's beside the point -- I'll use them all eventually). jThe whole time, I'm like "Oh god he's probably right; I've had a bad test for months and I'm totally torturing my poor fish!"

Well, long story short, the old test read the exact same as the two new ones. Nitrates in check, along with the other parameters.

As for the "zero nitrates" thing, I've re-read my post to make sure I didn't imply this. All I said and meant to imply was the levels were "nearly zero, almost zero, virtually zero, reading zero..." If there are living organisms in the water (even microbacteria, diatoms, etc) there will be waste from those organisms in that water. The tests may not be able to distinguish between 0-1ppm, and therefore read zero.

I also wasn't trying to imply that the way I manage nitrates is the answer for anyone else. I just wanted to share my experience with plants, because a few peoples' comments about them rubbed me the wrong way (because I'm such a HUGE fan of plants in the aquarium).

Believe me, Mike, I have been very surprised about the levels just like you are. I don't think that the plants alone are the reason for the low levels. Here are some other likely contributors:
1.) Small species of fauna -- the largest I currently have are rope fish (erpetoichthys calabaricus) that are about 9" (but very thin). The rest of my fish are smaller, and produce minimal waste.
2.) Cleanup crew -- I try to keep shrimp and algae eaters in my tanks to control what the others leave behind. This means that nutrients get absorbed by them rather than the water.
3.) Algae -- though I don't have much, most algae that grows stays in the tank. I only scrub the front glass, and only occasionally. Sometimes I clean a rock or two, but only if it becomes so covered it's unattractive. As you know algae, like plants, absorbs nutrients from the water.
4.) LOTS of plants -- Even though most of my plants are slow growers, the sheer quantity of flora provides substantial nutrient absorption. I also use several marimo balls in my tanks, and add plants to my hanging filters. The marimo balls are slow growing, but quite large and hardy.
3.) Limited feeding -- I try not to overfeed, and drop in a minimal amount of food a few times a day. It's enough that everyone gets some, but nobody gets too much. What does get left behind is usually picked up by the cleanup crew.
4.) Excessive filtration -- I run filters capable of filtering much larger volumes. My high-tech 75 runs an FX4 (rated at 700gph/up to 250g tank). My low-tech 75 currently runs two Emperor 400s (400gph/ tanks up to 80g EACH). The emperors also have plants in them, which grow like crazy. It's a great way to propagate houseplants! The low-tech 29 runs a Fluval 406 (383gph/up to 100g tanks). In my opinion, these filters are all overkill for the tanks they're on, but they've been working like a charm and I don't need to clean them so often.

One final note I should make is that I do occasionally overdose ferts, and notice a nitrate spike (>40ppm). Presumably this happens because the plants get enough nutrients from the ferts that they stop absorbing the other stuff. When this happens I will perform a 10-20% WC immediately (once I see the spike in a test, maybe a few hours later), then test again shortly after, performing another (usually smaller) WC if necessary.

ALSO, the 29 is new (installed about 3 weeks ago), and I will add more plants in the near future. As of now, the only reason I don't WC more is because there are 3 small fish and a massive filter. I ran the filter on my high-tech 75 (to build up the biofiltration) for months prior to setting up the 29.

And as for being reluctant to change water, I'm not. I simply don't feel it's needed as long as all my parameters are in check. And I check them VERY FREQUENTLY (usually once a day). I would rather leave my nutrients in the water than have to dose more after massive WCs. If I'm bored, I add to my tanks, propagate plants, and rearrange decorations (I've lately become obsessed with making caves/rock formations for my catfish). Also, these tanks are a bit of an experiment for me. I'm really trying to see if I can create a completely self-sufficient ecosystem, as others have in nano-tanks, heavily planted with shrimp and/or very small fish. If I ever noticed any signs of stress in my fish (or, God-forbid, death) I would change my thinking on the matter. As of now, the fish are all very happy, playful, and peaceful. Several of them even show signs of courtship. I'll continue to update, if you all like, but it seems the general concensus here is, "that's bad and you're wrong." And maybe you're right, but I'll let my results do the talking.

BTW, Nick, very nice pics. I can't figure out how to enlarge them; could you post a bigger size, or maybe send me some pics or a link to bigger ones? Again, I'm new here and not sure if there's an easy way for me to view an enlarged version.

Regards

Forgive my skepticism, but your tanks seem to be sparsely planted with slow growing plants. I have a more heavily planted tank and nitrates will still rise even with routine water changes.


You also mention that you 'over filter' and this helps contribute to low nitrates.
"4.) Excessive filtration -- I run filters capable of filtering much larger volumes. My high-tech 75 runs an FX4 (rated at 700gph/up to 250g tank)."
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This is a common misconception.
Filtration merely removes detritus and uneaten food from the tank proper giving the appearance of cleaner water. However, with erosion and decomposition, this material continues to break down and lower the actual quality of the water. The same is pretty much true for 'clean-up crews' as they produce waste and although beneficial, they don't really improve the quality of the water chemistry.
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I'm thinking it wouldn't hurt to get a 3rd party test for nitrates, perhaps at your LFS, but that's up to you.
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Again, in addition to replenishing minerals, the solution to pollution is dilution and without routine partial water changes, most aquariums are on their way to old tank syndrome. Sadly, many end up in the garage, basement, or on Craigs list! When I think of how little time it takes for the weekly partial water change, I just don't understand why hobbyist's try to cheat.

Regards, Mike

AbbeysDad said:

...Again, in addition to replenishing minerals, the solution to pollution is dilution and without routine partial water changes, most aquariums are on their way to old tank syndrome...

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I like it, the solution to pollution is dilution

Geigetron343 said:

And as for being reluctant to change water, I'm not. I simply don't feel it's needed as long as all my parameters are in check. And I check them VERY FREQUENTLY (usually once a day). I would rather leave my nutrients in the water than have to dose more after massive WCs.

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This is a very false myth. The point of doing regular substantial water changes is maintaining water stability. Once nitrates rise, the fish have been impacted; prevention is better than cure, since these issues do affect fish permanently. And the goal should be to have nitrates as low as possible (zero would be ideal) but certainly never above 20 ppm, and this level is serious for some species.

There are issues with water than cannot be tested. There is no test for pheromones and allomones that I am aware of, and these can have issues for fish. Aside from that, water deteriorates over time, and no filtration can reverse this.

Okay folks, I'm going to post once more, and be done with this thread. It's starting to frustrate me. I'm not a fish biologist, so I won't promote my methods as totally proper or an answer to nitrates, nor will I speak for anyone but myself. Furthermore, I am totally comfortable keeping my current schedule so long as my plants grow and my fish show no signs of stress.

Byron said:

This is a very false myth.

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What is the myth, what makes it false, and what evidence have you found that can support your claim? The things I'm claiming are all observational phenomena happening in my own home, right before my eyes. Please explain/expand/substantiate your words if you're going to shout "WRONG" at people who are trying to have a dialogue. Where are you getting your numbers from (never above 20ppm)? I've looked at countless threads online and talked to a couple of professors about the issue, and the general consensus I've reached is 10-30ppm is ideal for a plant AND fish tank. I understand that some species of fish don't tolerate high nitrate levels well, but I'm not raising those fish. Considering my levels are consistently within the EPAs drinking water standards, I'm going to assume it's relatively safe for fish. If I EVER notice a single fish in distress, I WILL change my routine.

The purpose of my post was to provide information about the threads topic ("reducing nitrate without water changes"). I've provided my methods for reducing nitrate WITHOUT water changes, hoping that it may help someone figure out how they want to go about their business. Does anybody have anything to add to the discussion besides "change your water?"

No one is saying your plants are not growing well. But your other assumptions are incorrect.

EPA standards for human drinking water cannot be used for fish. Copper as another example at "safe" human levels in water supplies will kill fish in an aquarium. The relationship of fish to their aquatic environment is unlike the relationship of any terrestrial animal to its environment, with the possible exception of amphibians. Once we understand that complex relationship, it is much easier to see how substances such as nitrates do detrimentally affect fish.

The fact that nitrate in natural tropical waters are zero or at most less than 1 ppm should tell us something. Freshwater fish species have evolved to function in very specific environments, which includes the water chemistry. The fish's physiology functions best in the natural environment for which it was designed; as soon as abnormalities appear, they begin to impact the function. The limit of 20 ppm nitrate is standard from every reliable ichthyologist and biologist in the hobby. Some fish species are more susceptible than others, and the actual level plus the duration of the exposure can factor in, but in the final analysis nitrate is a form of nitrogen the same as ammonia and nitrite and these are all toxic. Cichlid authorities are now suggesting nitrates may be the underlying issue with various problems, and all advise keeping nitrates below 20 ppm for cichlids.

Waiting until you see fish in distress is waiting far too long, as the damage has already been done. The initial effect of nitrate is to weaken the fish generally, making it much more susceptible to other issues down the road. There are no external signs, and if the fish were to be killed and a necropsy performed, quite likely nothing would show up internally, at least at the initial stages. But that does not mean the fish is/was not being impacted. Stress itself results from such issues, and stress is the direct cause of 95% of all fish diseases. Most studies on nitrates and fish have been concerned with food fish, but no one doubts the findings nor their application to fish generally. This weakening can go on for some time, and along the way other aspects of the fish's physiology will be affected. The fish's immune system will be weakened; we know without question this is a result of stress for fish, and the cumulative effect of problems can all be traced back to nitrates. Again, the species, the level, and the exposure time all factor in. Just because each of us cannot see the fish's efforts to cope with or overcome the conditions does not mean that is not occurring; we can logically assume it is, when we place the fish in such an environment.

Plants are not all that effective at using nitrates. To begin with, most aquatic species prefer nitrogen as ammonium, and will readily assimilate ammonia/ammonium. They are able to do this faster than the bacteria, according to scientifically-controlled studies, and this is why nitrates are often low in planted tanks. The plants use the ammonia/ammonium, and nitrite is not a by-product, so nitrate is also not produced. If ammonia/ammonium is insufficient for the plants' needs, in balance with light and other nutrients, they will then turn to nitrite and nitrate; some studies suggest nitrite is chosen over nitrate, but this is not well documented. But in either case, the plants only turn to these when ammonia/ammonium is insufficient because the plant has to take up the nitrite/nitrate and convert it back into ammonium in order to use it, and this takes additional energy that is not then put into growth. This applies to natural or low-tech planted tanks. As soon as you get into high-tech, with mega light and frequent fertilization, nitrate is the safer additive than ammonia, though some fertilizers such as Seachem's Flourish Comprehensive do contain ammonium. Unfortunately, the fish lose out in such tanks. It is not surprising that many high-tech planted tank enthusiasts have few and often no fish in their aquatic gardens.

As for nitrate reduction without water changes, this is a fallacy in most cases. Nitrates occurring within the aquarium, i.e., not introduced with the source water, can and should be controlled. Not overstocking, not inappropriately stocking (wrong combination of species, etc), not overfeeding, regular significant water changes, filter cleanings, and live plants can all help. I explained above how plants do this, but it is limited. And if the biological system is in balance, all factors considered, nitrates will be very low and remain consistent from water change to water change; any rise between is a sign that the biology is not in balance.

Okay, thank you. So assuming nitrates aren’t great for fish and ammonia is worse... and plants favor ammonia over nitrates, How do you suggest making them both happy living together? Are there any particular articles or threads you could suggest? (This isn’t the thread for that discussion)
Thanks

You could do worse than reducing your filtration. Plants take up ammonia without producing nitrates. The filter takes up ammonia and converts it to nitrates. So the bacteria in your filter and the plants are competing for the same food source.

Geigetron343 said:

Okay, thank you. So assuming nitrates aren’t great for fish and ammonia is worse... and plants favor ammonia over nitrates, How do you suggest making them both happy living together? Are there any particular articles or threads you could suggest? (This isn’t the thread for that discussion)
Thanks

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You're very welcome.

There is considerable ammonia being generated in most aquariums with fish. Aside from respiration, there is the breakdown of organics in the substrate (primarily) and the filter. The natural or low-tech approach works because plants are able to utilize this ammonia/ammonium and they are very adept at it. Floating plants are often referred to as "ammonia sinks" because of the amount of ammonia they can assimilate. In the average (but balanced) aquarium, the fish load is going to provide all the ammonia/ammonium the plants need. The only time this becomes unworkable is when we move to high-tech systems.

Light drives photosynthesis, and plants will photosynthesize to the max provided all nutrients are available. Liebig's law of minimum--that plant growth is controlled not by the total amount of resources available but by the resource that is scarcest, or limited--kicks in and photosynthesis slows and could even cease depending upon the balance. Providing bright lighting (which is frequently harmful to fish, by the way) and mega fertilization including diffused CO2 pushes the envelope beyond reasonable and that is where difficulty for fish occurs. Aquatic gardens are not aquaria for fish; you will never see such aquascapes in nature. There is now evidence that diffused CO2 is detrimental to fish, and we know bright lighting is bothersome. But the photos in your post do not show high-tech systems, so in these tanks there is no reason why ammonia/ammonium should not be adequate. And nitrate can be kept low; it is not uncommon to have zero nitrate in fairly heavily planted natural/low-tech tanks with fish. My own, which I admit are fairly well stocked, always test in the 0 to 5 ppm range.

My goal is fish first, plants second. Knowing my fish do not appreciate bright light, I use low-moderate lighting, and I have floating plants in all tanks. The lower plants are those that will manage under the conditions I provide; if I try this or that plant and it falls apart, I move on to another species. It limits what I can have, but that is OK with me because I care about the fish that are forced into the environment I create. Some photos of my tanks over the past few years may illustrate; there is no CO2 in any form being added, and minimal liquid fertilizer. And weekly single water changes of 60-70%.

EDIT. While I was typing, seangee posted a very pertinent point...filtration competes with plants, so biological filtration should not be "encouraged." I use simple sponge filters in all my tanks except the 90g.

How do you suggest making them both happy living together?

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Water changes.