Do Nitrates matter?

Jetfixr · Jan 10, 2022

I have been out of reefing for about 10 years and just getting back into it. So I haven't cycled a tank in ages. I am seeing some conflicting info on nitrites. One source is saying dose 2 ppm ammonia and within 24 hours the ammonia should be converted to nitrites, and then nitrates, because both ammonia and nitrites are toxic to fish but they can tolerate nitrates easily. I see other sources saying the ammonia should be at zero within 24 hours and nitrites are not so important. I have set up a tank 3 weeks ago, used fritz turbo-start, I guess within 2 weeks the ammonia was being consumed in about 24 hours, but the nitrites were continuing to lag, seems like it is taking about an additional 48 hours for the nitrites to be zero. Not sure which source to believe.

Jekyl · Jan 10, 2022

If ammonia can go from 2ppm to 0 in 24 hours you're done. With the fritz turbo you should be fine either way. Do a water change to get nitrate in order and go fish shopping.

KK's Reef · Jan 10, 2022

I don't know the science behind it, but I think the nitrites stage is not long standing. Most people test for nitrates and ammonia only. If your tank is fully cycled, I would think nitrites would barely be detectable, but nitrates would be. If you already have corals in the tank, the nitrates could be consumed fairly quickly as well.

Randy Holmes-Farley · Jan 10, 2022

Nitrite is not toxic to marine fish at the levels we encounter. Concern about it is a carryover from freshwater systems, where it is quite toxic.

I discuss nitrite in detail here:

Nitrite and the Reef Aquarium by Randy Holmes-Farley - Reefkeeping.com