# Removing nitrate



## chrisnif (Aug 20, 2010)

I need to find a way to reduce nitrate without removing all the ferts I'm dosing. My nitrates were in the 40s!!! The plants are growing like noones business, but wow. I need to do something to clean that up.


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## Geniusdudekiran (Dec 6, 2010)

I'm afraid that only water changes will lower Nitrates. Please correct me if I'm wrong.


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## OverStocked (May 26, 2007)

NItrate of 40 is perfectly safe. There is nothing to actually indicate it is a problem. If your test kit isn't calibrated.... the reading may not be close. The ferts you dosing likely contain nitrates.... Plants uptake nitrogen pretty quickly, depending on other nutrients(light, co2, other ferts)


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## Capsaicin_MFK (Nov 15, 2009)

More plants. Well, more fast growing plants to be precise.


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## MarkMc (Apr 27, 2007)

Relax. What are your plants telling you? Forget what the inaccurate, uncalibrated cheap test kit is telling you.


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## justin182 (Aug 19, 2009)

Put more fast growing plants in there. For non planted tanks, use Seachem purigen to remove organic and nitrogenous waste.


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## Jeff5614 (Dec 29, 2005)

Water changes are a good and fast way to lower nitrates. A dirty filter is a good source of nitrates so if it has been a while you might consider cleaning it out. Also removing any dead or dying plants will help. Plants will remove nitrates unless they're unhealthy then they just contribute to the issue. Maintaining an effective biofilter will also help keep nitrates at bay. You may wonder how to maintain an effective biofilter. A few ways include not oversupplementing with CO2 during the day, aerating at night, using as much biomedia as possible in your filter and maintaining flow through your filter.

You could also consider moving toward a more nutritive substrate and a leaner water column since most nitrate would remain in the "soil" with lower levels in the water. This should still maintain excellent plant growth while lessening your concern about nitrate levels. This method seems to work very well for those with MTS and AS tanks.


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## Hoppy (Dec 24, 2005)

Dose mono potassium phosphate and trace elements. That will give the plants what they need, along with the nitrate, to grow well. The plants should then reduce the nitrates down to near zero, causing you to have to dose nitrates like the rest of us.

Back when people believed that phosphates were bad, a cause of algae, and they didn't dose it, when the finally became willing to dose phosphates, the next thing to happen was a shortage of nitrates. Plants won't grow at a normal growth rate unless they get all of the NPK and traces they need, plus a good carbon source.


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## boringname (Nov 11, 2010)

I think nitrates hurt fish by interfering with their oxygen intake. So if the fish aren't showing signs of being starved for oxygen then the nitrates aren't hurting them.


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## Diana (Jan 14, 2010)

Fish food is a big source of nitrates in a tank. Protein in fish food contains nitrogen. No matter if it is digested by fish or fungi. If you are also dosing nitrates as fertilizer (KNO3 or other), then just stop that one product that contains nitrate. Then do a big enough water change to seriously drop the nitrates. Then monitor the NO3 in the tank. 

a) Nitrates go up again and stay really high: You are feeding more nitrates than the plants can handle as fertilizer. More plants or less fish food. Improve other conditions for plants (CO2, light, other)

b) Nitrates creep up then hover between 5-20 ppm: Plants' use balances nitrate from fish food. Do not need to do anything. 

c) Nitrates never get higher than about 5 ppm: Start fertilizing with nitrates, but at a very low dose.


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## MarkMc (Apr 27, 2007)

boringname said:


> I think nitrates hurt fish by interfering with their oxygen intake. So if the fish aren't showing signs of being starved for oxygen then the nitrates aren't hurting them.


Is there some study that supports this? What levels are we talking about here?
Are you saying that high nitrates impair the ability to take in oxygen?


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## boringname (Nov 11, 2010)

MarkMc said:


> Is there some study that supports this? What levels are we talking about here?
> Are you saying that high nitrates impair the ability to take in oxygen?


I've never heard an explanation of why nitrites and nitrates hurt fish other than the explanation that it impairs the ability of fish cells to take oxygen out of the blood. 

Ammonia is different, it burns any exposed tissue.


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## MarkMc (Apr 27, 2007)

You're thinking of nitrite which is harmful to fish. Nitrate on the other hand, in normal amounts, is not. People add it to their tanks regularly.High nitrate levels from overfeeding, poor tank maintenance and the like is an indicator of other harmful things. Don't blame it on the nitrate.


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## reignOfFred (Jun 7, 2010)

different fish gave different tolerence to nitrate. some fish will suffer at levels as low as 10 while others can handle well over 100 if it builds gradually.


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## Hoppy (Dec 24, 2005)

reignOfFred said:


> different fish gave different tolerence to nitrate. some fish will suffer at levels as low as 10 while others can handle well over 100 if it builds gradually.


I don't believe that is true. All of us who dose nitrates in our planted tanks have fish, and a wide variety of different fish. We normally have 10 ppm and more nitrates, with the amount peaking every time we dose. I believe the toxic level for nitrates is closer to 200 ppm than to 100, for any commonly kept aquarium fish. And, we never add nitrates gradually - we dump in a 2-3 days dosage all at once.


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## MarkMc (Apr 27, 2007)

reignOfFred said:


> different fish gave different tolerence to nitrate. some fish will suffer at levels as low as 10 while others can handle well over 100 if it builds gradually.


Again, I'll restate what I've said before but differently. If you have a aquarium and it's apparent that the fish are stressed and you measure your nitrate and it's say, 30-50 ppm (according to an uncalibrated $15 test kit) _then_ you decide "hey, I need to do some much needed house cleaning-the filter is half plugged, there is a lot of organic material laying on the bottom, I haven't done a water change in months, I'm feeding too much, ect, ect. And you do that maintenance or you do a massive water change and low and behold the fish perk up, they start to look better. Sooooo.... what can we conclude from this scenario? High nitrate is bad!! Wrong! That would be the wrong conclusion. As Hoppy said, we add large doses of nitrate regularly with no adverse effects. What fish cannot stand 10ppm? Name the species and I'll bet someone will tell you they keep that species in 20-30ppm with no problem.


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## Qwop (Mar 14, 2011)

As others have said, I wouldn't be too worried about 40ppm NO3 unless you're actually having problems or seeing negative indicators.

Depending how you're dosing you may be able to reduce NO3 levels by dosing K2SO4 instead of KNO3. That way you would still get the potassium, without the nitrates, and sulphate levels to my understanding are pretty unrealistically difficult to dose to excess.

Otherwise, Seachem Matrix biomedia CLAIMS that it can harbour anaerobic bacteria to reduce nitrate levels. But I wouldn't bother switching to it for this reason.

Furthermore, the Encyclopedia of Aquarium Plants by Peter Hiscock has a brief section regarding the use of anaerobic filter media to remove nitrates. Though I've never actually heard of someone using this in practice, and I can foresee a lot of problems with it.

Otherwise the obvious suggestions like adding more fast growing plants, or reducing organic waste and debris in your filter, substrate, etc are all that's left.

While we're on the topic, if you have some KNO3, a pocket scale, some distilled water, and a 5gal container you can test your test kit to ensure its accuracy.


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## Diana (Jan 14, 2010)

http://www.waterboards.ca.gov/water_issues/programs/tmdl/records/region_2/2008/ref2426.pdf

Scroll down to Table 3

Fish EGGS and FRY are very sensitive to nitrate. 
Older fish (Fingerlings on up) are less sensitive. 
Mostly this was testing trout and salmon, but they also tested Guppies. 

Eggs and fry are sensitive to levels of nitrate under 10 ppm when measured as nitrate-nitrogen, slightly different from the way our test kits measure it. 
Guppy fry can handle 200ppm and other fish seem OK into the thousands of parts per million. These are LD50 numbers over a few days to a month: The level at which 50% of your fish die when they are exposed to that much for a few days up to 30 days. 

For example: Reading from table 3: Half of Guppy fry exposed to 200 ppm nitrate nitrogen die within 72 hours. 

At lower levels that are still quite high be aquarium standards the fish seem much less affected, and seem to live just fine. They just cannot reproduce very successfully because the eggs and fry are so sensitive. 

Nitrate seems to affect them the same as nitrite: When it enters the blood it causes methemoglobinemia. The catch phrase is 'WHEN it enters the blood' Most of the tolerance for high nitrate levels is because it does not enter the blood as easily as nitrite. 

How this applies to an aquarium is not clearly stated in that article. 
I would go along with the comment above: If high nitrate reading seems to cause problems for your fish/shrimp/frogs etc. the problem might not be the actual level of nitrate, but using nitrate as an indicator that some other parameter (that we do not normally test for) is getting too high, suggests that you do enough water changes to keep the nitrate at whatever level keeps your livestock happy. Such a water change should include some amount of 'gravel vacuuming' though in a planted tank this is more like ruffling the ground cover plants to loosen the fallen debris so it can be removed. Also includes cleaning the filter. 
If you are breeding, then keep the nitrate absolutely as low as possible.


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## MaStErFiShKeEps (Dec 6, 2010)

One word: Duckweed. Suck up the Nitrates then recycle the Duckweed


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## houstonhobby (Dec 12, 2008)

Use a BRS reactor filled with Purigen. Nitrates will go down.


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## snausage (Mar 8, 2010)

Give the filter a good cleaning and add a bag of purigen.


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## J-P (Oct 17, 2010)

if the tank has fish... why are you removing the only readable number that we can test for that states "your tank needs a water change"?

In a planted tank regardless of the value given, you should be doing regular water changes. If the number elevates to an unsafe number for the fish, it is usually an indicator of a serious imbalance.


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