NO3 staying very low in mature tank

[PedroYoung]

What causes low NO3? I have mature tank, 6+ yrs, and have what feels like chronically low NO3. Hanna tests at 0.1-0 ppm with PO4 between 0.02 and 0.07 ppm. Lots of fish, been trying to feed heavier. Never thought I'd be on the "my nutrients are too low" side of things. Acros are a bit washed looking. I usually do like 10% H2O changes weekly just to siphon detritus. Should I just feed heavier? Fish are not by any means scrawny. Considering either dosing aminos or some N2 source

Tank Parameters
200G display w/ 50G sump
Skimmer, refugium, GFO reactor, filter socks, 2 part additives, sporadically add MB7.

Tank pick by Peter Young, on Flickr

 

[arcangelreef32]

Your PO4 is already in the high range, I wouldnt add more food... Id look at dosing nitrate or ammonia if i were you.
Raise it slowly, get it in the 5-10 range and maintain it there.

 

[PedroYoung]

Your PO4 is already in the high range, I wouldnt add more food... Id look at dosing nitrate or ammonia if i were you.
Raise it slowly, get it in the 5-10 range and maintain it there.

Whoops, I edited the post to correct the missed decimal point.

 

[Randy Holmes-Farley]

It may be OK, bit if it were me, I'd feed more or dose N and P.

 

[arcangelreef32]

Whoops, I edited the post to correct the missed decimal point.

In that case, yes you can feed more for sure.. and if thats not enough or you feel like you're feeding too much.. just dose nitrate/ammonia and phosphate daily to bring your levels up to where you're comfortable.

 

[rishma]

I think your tank is a great candidate for dosing ammonium bicarbonate. I bet the corals will like it. Would be great experiment to see if the corals color up.

If you go that direction, keep an eye on phosphate. Many of us have seen phosphate drop when dosing ammonia.

The feed more option is good too, but I prefer dosing for an already well fed tank because you have more control.

 

[PedroYoung]

Thx all for the replies. I’m going to
1- dial back the refugium a bit
2- be a little more generous with the food
3- add some Neo-Nitro which was accidentally put in one of my BRS orders and they told me to keep it and get NO3 to at least 1ppm (slowly)

 

[Dan_P]

What causes low NO3? I have mature tank, 6+ yrs, and have what feels like chronically low NO3. Hanna tests at 0.1-0 ppm with PO4 between 0.02 and 0.07 ppm. Lots of fish, been trying to feed heavier. Never thought I'd be on the "my nutrients are too low" side of things. Acros are a bit washed looking. I usually do like 10% H2O changes weekly just to siphon detritus. Should I just feed heavier? Fish are not by any means scrawny. Considering either dosing aminos or some N2 source

Tank Parameters
200G display w/ 50G sump
Skimmer, refugium, GFO reactor, filter socks, 2 part additives, sporadically add MB7.

Tank pick by Peter Young, on Flickr

What is in the refugium?

 

[PedroYoung]

Cheato

 

[Dan_P]

Cheato

This is part or all of the answer. It seems your system might run fine without it. Not only that, the micro algae and slime that grow in the refugium are also quite capable of extracting nitrate from the system. If getting rid of the Cheato does not help, consider closing down the refugium.