If you aim for 0 nitrates, what do you feed your plants?

[Alice B]

I have never consistently used CO2 and run low-light plants, but I usually don't aim for zero nitrates. More like 40 and a monthly water change. Fish alive, anubias likes it.

I am struggling to get my 29 below 40ppm on nitrates, did a 50% water change last night so it might be at 20. 55 is at 10 ppm. Hex tank who knows, but it's happy at the moment.

Old school I learned plants needed nitrates. I don't want to spend a lot on plant food, I do have a bag of muriated potash in the garage and am contemplating dropping one crystal of that in my 55. I have Activate, and Envy for plants, and I bought Flourish Excel but haven't used it.

so what do you use? What is appropriate for a sketchy CO2 (I have a 20 lb canister for keeping SHB out of my honeycomb but I do NOT bring it in the house), low light, relatively low nitrates?

 

[seangee]

Aquatic plants use ammonia as a preferred source of nitrogen. They will only use nitrates if there is no ammonia available.
All 4 of my tanks have zero nitrates, ammonia is supplied by the fish. The plants use up the ammonia before the filter can deal with it so my nitrates are still zero just before my weekly water change.

Cons: The bacteria in my filter are probably dead from starvation
Pros: I never have to worry about my filter crashing, its only there for circulation and mechanical filtration.

 

[Colin_T]

Check your tap water for nitrates.

You need to keep nitrates as low as possible for long term fish health. Ideally you want nitrates on 0ppm, and less than 20ppm at all times.
You should do water changes more often to keep the nitrates down.

Unless your tank is full of fast growing true aquatic plants and only has a few small fish in, and it gets lots of light, there is no point adding carbon dioxide (CO2) or large amounts of fertiliser. There is plenty of CO2 in the average aquarium and it is produced continuously by fish, filter bacteria, and it gets into the water from the atmosphere.

I wouldn't add any garden fertilisers to an aquarium containing fish, shrimp or snails.

Anubias are marsh plants that grow slowly underwater and won't do anything to control nitrates. Floating plants like Water Sprite, Duckweed and Salvinia all do a much better job at reducing nutrients in an aquarium.

I used and Iron based liquid aquarium plant fertiliser (Sera Florena) and clay in the gravel in my plant tanks, but they had lots of light.

 

[Alice B]

I want my biological filter to have a little muscle. That is why I use undergravel filters. I like my water crystal clear, and if I suddenly have to add a bunch of fish, I want that filter to be able to handle that, so I may never aim for that 0 nitrates if that 0 nitrates means plants are doing everything and filter is dead. I don't know if that makes sense.

I fell for that zero filter processing in saltwater in about 2003, got rid of my undergravel and canister, put in sand, added extra pumps to blow water at my live rock. I ended up with a dead yellow tang, and very unhappy with my tank and I threw the sand out and put the undergravel and canister filter back on and life was good until WC got to heavy for me.

 

[Byron]

First issue is the condition of the fish. No fish that we keep as tropicals in an aquarium has nitrate in their habitat water, or if they do it is near-zero (I have never seen readings of habitats in Amazonia with even 1 ppm nitrate. Whatthis tells us is that the fish in our tank will unquestionably be healthier with zero or as low as possible and certainly not above 20ppm. Some fish, not just wild caught, are highly sensitive to nitrate--cichlids for example. The detrimental effect of nitrate on all fish can be considered as a basic weakening of the fish's physiology, leading to other issues which would--without the nitrates--be easily handled by the fish. The bottom line is, if you want to do what you can for healthy fish, keep nitrates as low as possible and certainly well below 20 ppm.

Second issue is that most aquatic plants prefer ammonia/ammonium, and they will readily assimilate this. Faster-growing plants take up more, and it is ongoing 24/7. Floating plants are sometimes called "ammonia sinks" for very good reason. From my discussions with Tom Barr, I learned that It is virtually impossible to add too many fish (I'm assuming "the norm" here, obviously a significantly overstocked tank to begin with will be different) that the ammonia will not be rapidly taken up, again assuming you have a decent number of plants including surface. And, this applies to low-tech. High-tech with mega light and diffused CO2 is a different thing entirely, and because no one is going to suggest adding straight ammonia, we use nitrate. But plants have to convert the nitrate back into ammonium in order to use it, another proof that they resort to nitrate as a "last" resort if everything else is available (light and nutrients).

Nitrates arriving with fresh water at changes is one issue, while nitrates solely occurring from the biological system is quite another. The latter should never occur, if the tank is properly stocked, not overfed, has live plants (just floating is fine), receives adequate water changes and filter cleanings.

 

[TwoTankAmin]

Cons: The bacteria in my filter are probably dead from starvation

Nope. The plants do not use ammonia (NH3), they use ammonium (NH₄⁺+). The bacteria use ammonia. Plants host the nitrifying bacteria on their stems and roots. And when the roots are in the anaerobic zone, some plants release oxygen from their roots to foster nitrification.

The pant can consume ammonium way faster than the bacteria can consume ammonia, bu they are both there. It is almost inpossible to have live planys and nor nitrifying bacteria in a tank. However, it is possible to have a tank with no plants or algae and only the bacteria to process the ammonia.

 

[StevenF]

Old school I learned plants needed nitrates.

This is actually not correct. Plants need Nitrogen (N) not nitrates (NO3). However potassium nitrate is the easiest to find and is less toxic than ammonia or nitrite. So many fertilizers use it. One alternative is Urea, CO(NH2)2.

I have and used it in my tank successfully. I have also read of others using it successfully..My understanding is that seichem nitrogen is mostly Urea with some KNO3. But there is a hazard that it could convert to ammonia. I have not seen that in my aquarium. Possibly because the plants consumed the ammonia before I ever noticed it.

But if you have measurable nitrate you might not need to add it for plants. is the nitrate coming from your fish or tap water?

I don't want to spend a lot on plant food, I do have a bag of muriated potash in the garage and am contemplating dropping one crystal of that in my 55. I have Activate, and Envy for plants, and I bought Flourish Excel but haven't used it.

Keep in mind plants nee 14 nutrients to grow. I just one is missing the plants don't grow. So If you add just one nutrient Potassium. Plants will use the potassium and the other nutrients in the water than then stop growing because of multiple deficiencies. you need all the nutrients.

One way to keep cost low is to only use the amount necessary. Anything over what is needed is waisted money. for a 55 gallon tank to achieve 10ppm NO3 you need about 3.3 grams of KNO3. A one pound bags of KNO3 Costs about $4 dollars on a mail order site. That is enough for 151 10ppm doses done once at each water change. That is enough for several years. So the best way to dose a fertilize is to Use a fertilizer calculator to determine how much to add and them measure it out and add it. So $100 of fertilizer ingredients can last a long time. If you buy a liquid fertilizer you end up spending a lot of money for mostly water and there is no guarantee that the company is making a good product that will work in your tank.

there is one other way which is to use the waist from your fish to fertilize the water.Generally this involves fewer water changes so fish waist build up to allow plant growth. Not this involves some risk since stuff other than plant nutrients can build up and become toxic. This has been used in larger tanks like your 55 gallon but is diffiult to do in smaller tanks.

You might want to try a floating plant first such as Salvnia or red root floaters. If these grow without evidence of a neutrient deficiency such as yellow or damaged leaves you might alreay have enough nutrients foursome plants. If the plants don't look found it might be possible to figure out what nutrient is missing and adjust for that.

At the point it all depends on what you want to do . but there isn't enough information in your post about what you want.

 

[Alice B]

Thank you for your reply. I want a nice tank, that is relatively low maintenance, without cyanobacteria or problem algae species. I was contemplating the potassium because I had some red cyano, but I have reduced light - tank came with bright LED's, I picked up a fluorescent fixture, reduced hours of light, reduced feeding and cleaned the tank up well. I suspect I do not have cyanobacteria since the changes, but for safety I did move my albino pleco female out to another tank. I want to enjoy my fish. I use undergravel filtration and have never really fertilized my anubias and java before. The fish provide the CO2 and the nitrate. I don't need a prize winning tank, I just need one that won't die when I am gone 10 hours a day in spring and fall

 

[Colin_T]

I wouldn't be adding anything for Anubias or Java Fern.

To keep Cyanobacteria (BGA) away, keep the tank clean. Floating can help reduce the BGA occurring.

 

[Alice B]

I have some crypts I think and that's what I put the fertilizer pill in for. I've raised giant Anubias and never fertilized, I just feed the fish and do a monthly water change (I know it's terrible) I don't have blue green algae. But if I want it it seems like all I have to do is put in a piece of limestone. Our ph is so high around here that lime leaching pushes it over the top

 

[Alice B]

This is actually not correct. Plants need Nitrogen (N) not nitrates (NO3). However potassium nitrate is the easiest to find and is less toxic than ammonia or nitrite. So many fertilizers use it. One alternative is Urea, CO(NH2)2.

I have and used it in my tank successfully. I have also read of others using it successfully..My understanding is that seichem nitrogen is mostly Urea with some KNO3. But there is a hazard that it could convert to ammonia. I have not seen that in my aquarium. Possibly because the plants consumed the ammonia before I ever noticed it.

But if you have measurable nitrate you might not need to add it for plants. is the nitrate coming from your fish or tap water?

I just tested my tap water for nitrates, and nitrates are zero in it. So nitrates are coming from my fish. Now I have more plants than fish in my little 29. I took the guppies out, mollies were eating the babies anyhow and the nitrates were 80 in early June, so I cut the population and started water changes.

 

[Spyro]

I just tested my tap water for nitrates, and nitrates are zero in it. So nitrates are coming from my fish. Now I have more plants than fish in my little 29. I took the guppies out, mollies were eating the babies anyhow and the nitrates were 80 in early June, so I cut the population and started water changes.

You need to dose Potassium, Phosphates and micro-elements ferts for Java Fern and Anubias to take care of nitrates for you.
Otherwise they'll just grow slower as per limiting factor of Potassium, etc.
They don't compensate by producing lower quality leaves and steam when having deficiency and thus will not absorb nitrates if there isn't sufficient Potassium, etc.
If you don't want to fertilize: a lot of steam plants and floating plants will compensate with nutrient unbalance by producing weaker leaves/steams while still using up nitrates.
Most fish foods don't have enough phosphates and Potassium for Anubias and Java Fern to take up all the nitrates produced as waste.
GL

 

[TwoTankAmin]

There is a difference between adding fertilizers for plants vs the creation of ammonia and nitrate in aquariums. Yes plants do need nitrogen and also ammonia is created in tanks by fish exhaling and pooping. It is created by the breaking down of organic matter- like fish food, dead plant leaves etc.

Aquatic plants can get needed nitrogen from the ammonium that most ammonia becomes in water. They can also use the nitrogen in nitrate. And yes they can use the nitrogen in urea, but that has to be added to a tank. However, when it comes to any ammonia/ammonium/nitrate beign made available in a tank, the plants will use the ammonium not the ammonia while the bacteria will use the ammonia. When they do this the end result is nitrate and, if they need to use it, plants will do so. However, they have to convert it back to ammonia which means it supplies less energy for the plant.

A few aquatic plants prefer nitrate as their nitrogen source. Below is just one example.

Jampeetong, A. and Brix, H., 2009. Nitrogen nutrition of Salvinia natans: Effects of inorganic nitrogen form on growth, morphology, nitrate reductase activity and uptake kinetics of ammonium and nitrate. Aquatic botany, 90(1), pp.67-73.

Abstract​

In this study we assessed the growth, morphological responses, and N uptake kinetics of Salvinia natans when supplied with nitrogen as NO3−, NH4+, or both at equimolar concentrations (500 μM). Plants supplied with only NO3− had lower growth rates (0.17 ± 0.01 g g−1 d−1), shorter roots, smaller leaves with less chlorophyll than plants supplied with NH4+ alone or in combination with NO3− (RGR = 0.28 ± 0.01 g g−1 d−1). Ammonium was the preferred form of N taken up. The maximal rate of NH4+ uptake (Vmax) was 6–14 times higher than the maximal uptake rate of NO3− and the minimum concentration for uptake (Cmin) was lower for NH4+ than for NO3−. Plants supplied with NO3− had elevated nitrate reductase activity (NRA) particularly in the roots showing that NO3− was primarily reduced in the roots, but NRA levels were generally low (<4 μmol NO2− g−1 DW h−1). Under natural growth conditions NH4+ is probably the main N source for S. natans, but plants probably also exploit NO3− when NH4+ concentrations are low. This is suggested based on the observation that the plants maintain high NRA in the roots at relatively high NH4+ levels in the water, even though the uptake capacity for NO3− is reduced under these conditions.

Basically, plants need N as pointed out, but when that is offered in the form of ammonia, which in water becomes mostly NH4, the plants use that not the NH3. The issue with nitrate as as an N source for plants is that it must be reduced to ammonia inside the plant in order for it to be used. This requires the expending of energy to accomplish the reduction. The result is that nitrate provides less energy to most plants.

(Edited for grammar and spelling only)

 

[StevenF]

The fish provide the CO2 and the nitrate. I don't need a prize winning tank, I just need one that won't die when I am gone 10 hours a day in spring and fall

If your fish are producing most of the nitrate then it is likely that you also have high phosphate level. You might want to consider getting a phosphate test kit.

The macro nutrients plants need are Nitrogen (N), Potassium (K), Calcium (Ca), Magnesium (Mg), Phosphorous (P), Sulfur (S), Chlorine (Cl).

I looked up the water quality report for Fort Worth Texas and it appears your Ca, Mg,S,Cl levels are fine. Mg levels might be a little low but I wouldn't add it unless a magnesium deficiency is suspected. Generally I aim for a 1 PPM P, 5 PPM Mg. Epsom salt ( Magnesium Sulfate ) is commonly used. Some people with a high fish load report they need extra Potassium. If you need it you can use potassium sulfate or potassium chloride If you need it I would try 5 PPM. Use this fertilizer calculator to determine how much to add to your tank to reach these targets. You can get most of these ingredients at LoudWolf.com

If your plant don't don't well with the above information you probably have to dose some micros. Micro nutrients are Iron (Fe), Manganese (Mn), Boron (B), Zinc (Zn), Copper (Cu), Molybdenum (Mo), and Nickel (Ni).

Nickel and Molybdenum are the least used nutrients plants need. 0.001PPM is sufficient for these and there is a good change you have enough of theme from your tap water or fish waste. If your home has Copper pipes you should have enough copper in your tap water. Iron it typically deficient in many tanks. Fe DTPA is the best iron fertilizer it is stable to a PH of about 8. The water quality report says your PH is about 8. But the PH of your tank is more important.and I don't know that. For Micros dose to the following levels.
Fe 0.1 PPM, Mn 0.05 PPM, B .02 PPM, Zn 0.02 PPM, Cu 0.006 PPM, Due to your high kH all but B of these should be chelated nutrients meaning Fe DTPA, Mn EDTA, Zn EDTA, and Cu EDTA. These are typically found at hydroponics stores only but mainly in 1lb minimum quantities so these may be more expensive. For B use Boric acid but you migit not need this one. Your fish might be producing enough.

 

[Alice B]

I do need a phosphate test. Not sure which one, the old Red Sea tests seem to be gone. Salifert I think was difficult to use last time I had one, have you tried API's? When I do monthly water changes (my former habit and on my hex tank my current habit), my pH is around 7.5 in the aquariums. I go to larger or more frequent water changes my fish will get used to 8. And they do, but it isn't prime for breeding corydoras or albino bristle nose.