Zero nitrates: good or bad?

[ScubaSkeets]

Hi folks!
My 125G is currently a FOWLR tank.

A week-week ¹/² ago, my nitrates were approx 50ppm, per Salifert and API. I added a jar of Seachem de-nitrate into my HOB refugium (I'm running a canister filter and since the de-nitrate calls for a low flow, I put it into my refugium).
I just tested the nitrates again (Salifert and API) and they are at zero! Phosphates are at 2.0, per API. Nitrites and ammonia are 0, per Salifert.

I was always of the understanding that zero (or at least <0.2ppm) were what we thrived for. However, before posting this, I searched R2R and found some posts where people seemed to be concerned about zero nitrates.

So now, I'm confused. Should it be <0.2ppm, or not?
Does a reef tank require nitrates that a FOWLR tank does not?

 

[dvgyfresh]

Depends on tank , for a fowlr tank nitrates aren’t as important but I would still not let them hit zero for the algae who will not be named (Dino’s)

And for example I run an anemone tank and I want nitrates around 10-20ppm

 

[dvgyfresh]

Also 2ppm phosphate seems very high but API is horrible for testing (it’s a yes/no not a number value) for phosphate I would recommend Hanna checker and to get them <1ppm

 

[littlebeard]

IMHO zero nitrates + starting with dry baserock = Cyno/dino.

2nd, I believe prime binds to nitrates so I think it merely masks it's presence.

Some people have been able to run a low levels, but I think it requires liverock with a mature bacteria biome.

 

[Biokabe]

It really does depend on the type of tank you have. For a FOWLR tank, you just need your nitrates to be not-toxic to your fish. Anything from 0-75 ppm is likely going to be fine for just about any fish in the sea.

You only really start caring about nitrates when you have sessile invertebrates (corals, anemones, clams, gorgonians, etc) in your tank. They depend, at least in part, on nitrates in order to grow. Without sufficient nitrates, their nutritional needs aren't met and they begin to decline.

However, you don't want too much either, because nitrates that are too high can quickly become toxic, and they can also fuel algae growth, which can smother corals. So for a reef tank, you want some nitrates and phosphates, but not too much. Depending on what you're keeping, you shoot for 5-20 ppm for nitrates, and about 1/20th of that for phosphates.

 

[Poof No Eyebrows]

As has been said, depends on what's in the tank. My small tank is primarily zoas and they love their nitrates. My largest has anemones and they are nowhere near as tolerant. Definitely want some detectable amount though. Otherwise you'll end up fighting algae/bacteria issues like dynos.

 

[Uncle99]

Corals are a minor consumer of trace phosphate, to low, they starve out, too high limits growth potential.
I like to keep phosphate around 0.07-.1ppm, nitrate below 15ppm.