Thoughts about Nitrates

hawkinsrgk · Apr 22, 2016

I have been reading a ton of information due to what I perceive as having high nitrates in my tank. For maybe the last two years I ran 6 cups of GFO and 2 cups of carbon in my 380 gallon (water) system. My corals seemed pale and the chaeto was pale to the point I think it was starting to die. So every month I would add less and less GFO/carbon to the system because the system was too clean. Eventually I took the reactors offline and left it like that for a couple of months. Then, I started to dose nitrate and was shooting for somewhere around 2ppm nitrate. I kept dosing nitrate until I hit the 5ppm mark and stopped worrying about it for around 5 months. Around a month ago, I check for nitrates and was at the 50ppm mark. After a lot of reading I started dosing vinegar and I am up to about 90ml vinegar spread out every hour with a dosing pump.

One thing I noticed was if you read a lot of threads from around the 2005-2010 timeframe all the rage was to get nitrates down to 0. I would see you tube videos and read threads that would say something to the effect of my nitrates got up to 160, and through large water changes I was able to get it down to 10ppm. Unfortunately, doing this killed just about everything in my tank, but I am so glad I was able to get it down.

So after all of that here is my question. Is the amount of nitrates in a reef tank really something to be that concerned about assuming your not at the extremes?

Thanks
Randy

Kungpaoshizi · Apr 22, 2016

Really depends on what you're housing... But given nitrates will drive unwanted algae growth, it's best to keep them in check, reasonably. It's less of a problem for fish, but for sps it can cause undue stress as their natural environment is devoid of nitrate.

Randy Holmes-Farley · Apr 22, 2016

Elevated nitrate can also encourage zoox growth, which can brown corals.

I recommend aiming for about 0.2 to 2 ppm. The low end is less desirable for an SPS tank with alk on the high side. The low end can go even lower with sufficient organic N forms dosed. On the higher end, a few ppm is usually OK, but it depends on the levels of other nutrients such as phosphate or iron which can limit algae growth.

FWIW, you mention use of GFO, but that does not reduce nitrate, only phosphate.