Nitrate problem

[rg]

I have a 125 gallon tank with a 55 gallon sump/refugium. For a skimmer i have an asm g-3. My fish are: 2 chromis, yellow tang, blue hippo, powder blue, 1 lyretail anthia, angelfish, damsel, scissortail goby, and three clown fish. My nitrates are at 20 but every time i do a 30% water change, nitrates still stay at 20. I have a r/o unit and it reads 004 on the T.D.S. What could be the problem be since the nitrates dont go down. All the corals and fish are doing fine. Any suggestions?

[FireWater]

Have you double checked your test kit or results with a different test kit? How about cleaning sump and checking for detritus anywhere? What about other parameter results?

[rg]

Haven't tried with a different test kit, sump is clean and no detritus, ammonia and nitrites are at zero.

[FireWater]

I would double check the results with another test kit or take it somewhere to get tested for you. If they come up the same then it will take a systematic approach to track down where they are coming from.

[Jynxgirl]

Another quick way to test if your test kit is not working right. Do a test on distilled water from your r/o water. I have learned if something doesnt read right, I test regular water and see what the test reads.

[rg]

it reads 0

[ErikH]

Use a powerhead to spray your rocks down, there has to be a source of the nitrates. Eliminate that, then suck up as much of the detritus as possible while it is in the water column. Skim wet for a few days, and check again. Usually you'll have a bad reagent when your levels go off the charts, eg. a blood red reading on a nitrate kit (160+)

HTH