Need help to lower nitrate level in fishtank?

Question

We have a 40 gallon salt water tank with two fish. We feed the fish every two or three days. We do a 10 to 20% water change once a week sometimes once every two weeks. However the nitrate levels are sky high. They go down after the water change, but they go up soon after. Any idea what we should do?

Answer 1

The only safe way to remove nitrate, the final stage in a cycle, is to do water changes. If you are over stocked or are feeding too much then it will cause the nitrate to rise too high. Fix that problem and your nitrate won't rise too high too fast.

Answer 2

Keep changing the water... Prime will NOT reduce the nitrate level, although it may help by making it less toxic. A 25% water change MUST reduce the nitrate level, as you physically poured some of the nitrate down the drain. Just keep doing them, and the nitrate keeps going down the drain. BUT - don't be tempted to do a sudden large change. If the level is actually that high then the tank has been neglected for quite some time. Doing a sudden large change can shock the fish. Yes they are going to cleaner water, but the sudden change is stressful. Do a smaller change every day and fix the problem over a week. Also double check your test results, as a reading of 200 is crazy high. Try testing your tap water, as that should be under 10ppm. If that tests sensible, then maybe your tank has go that high, and in that case, keep changing that water. Ian

Answer 3

Oh poor fish... he is right, you are doing it way to often, which is why your nitrates are so high.
I can't stress this enough, bacteria bacteria bacteria. Is this a new tank?
Well even if it isn’t. Go to your local store and get some live bacteria, I happen to love the brand Cycle as it is very concentrated, get a small bottle and poor the entire thing in. poor it over your filter as well so that some will stay trapped there and grow. It will not harm your fish, but your water changes and high nitrates will.
We use this trick in the industry, it works like a charm, it may take about three days, time unfortunately your fish may not have,
Because you have done many water changes you are messing with the natural cycle process needed. Every time you do a water cycle as often as you have, you are simply starting the process all over again. STOP!
Maintaining a population of bacteria that can convert ammonia into nitrite is an important part of your tank's water chemistry; a process known as biological filtration. Biological filtration will occur naturally in most tanks that have been up and running for a couple of months. New aquarium filters often contain a special area or wheel made specifically for providing an optimal habitat for growing these bacteria. While the bacteria will live in a traditional filter and on rocks in the aquarium, these new biological filters harbor a much larger colony and can therefore do a better job of removing ammonia and nitrites.
If you have a new tank, go to the store or to the person who told you to do this and shake your finger in their face, lol, they have wronged you. So often the case in most of these pet stores, be care and be educated, before talking to those guys.
I have even used bacteria in my saltwater tanks daily, when ever I get a spike, and freshwater alike been in the field and study of fishes for a long time. Please oh please stop trying to keep your tank so clean!

Answer 4

I don't agree with the two previous posters. You have a high nitrate problem, not ammonia & nitrite problem. Your cycle is working fine (having high nitrates is proof of this).

You need better methods of exporting the nitrate from your tank.

You need to conduct larger and/or more frequent water changes. You might want to do one 40% water change now, and 25%-30% weekly. In a salt water fish only tank you'll want to keep nitrates below 20ppm (preferably under 10ppm); if you have corals than you want nitrates at 10ppm or below (preferably 0ppm).

If you don't have one yet, get a protein skimmer. Quality skimmers cost a lot but are worth it. They remove a lot of dissolved organic compounds, etc before they have an opportunity to break down into ammonia, nitrite and nitrate.

If you have a refugium or sump, load it with macroalgae (chaetomorpha, etc), as it assists in the exportation of nitrate from your tank.

1 to 2 pounds of live rock per gallon and a deep sand bed may assist in lowering nitrate levels as well.

Answer 5

are you adding anything to your water changes to get the chlorine and other hard toxics out? I use Stress Coat with Aloe Vera. It treats the water and the fish. I would recomend two water changes a week until you get the level down. I went to a specialist when I had my problem, and he said avoid adding chemicals whenever possible. You not only have to get the levels down from in your tank, but in your filter too. Good luck with that. We feed our fish two times a day, we just feed them as much as they will eat and scoop out the left overs. Do you have a bottom feeder? Snails? crabs? Nitrate is caused by old food in the tank

Answer 6

You are doing your water changes way to often they should only be done once a month your fish tank needs time to build up the beneficial bacteria that breaks down ammonia and wast products(Nitrate). Also you should buy a small tank for know and put the fish in their and fill up with some of the water from your fish tank and the rest with new water. Let the ammonia eating bacteria build up and you will see that your water will be clear and the levels will go down this will take about a month to happen. I would also consider a larger filtering system.

Answer 7

1-2 pounds of live rock per gallon always helps cycle my tank best. I added live rock to my tank and it was fully cycled in 3 days. I never have had a problem with nitrates because all the good bacteria in the rocks just goes to town on it. Live rock is a bit expensive but is totally worth it.