Is my tank chemistry unbalanced leading to poor coral health?

alyee5 · Aug 20, 2017

My acans and favia and "easy" SPS frags all died a slow death over the last few months...Duncan and hammer coral and gsp doing ok but slow growth. I am attributing this to an imbalance of "high" nitrates (10-25 using Salifert) vs 0 Phosphate (using ULR Hannah checker).

My nitrates used to be <5ish when the Acans were doing fine (new heads and good extension). I am not sure what caused my system to stabilize at 25 and 0--I am thinking it was when I put a GFO/C reactor online when I started to see hair algae??

Even with no reactor now for 2 months, several water changes, vacuumed sand bed (and partial removal of sand), overflow cleaning, frequent filter sock changing, good skimming, clean sump, scrubbed rocks...I can not get my nitrates down. I have 7 fish in a 100 gallon DT/30 gallon sump with 70lbs rock and a large block of media pure. I feed 1 sheet of seaweed and about 1 cube frozen or 2 pinches of pellet/flake a day.

Lighting are 2 Kessils A360w's above a 4 ft tank running about 10 hrs with max at 45%. Calcium is 450 and alk 8.2 and Mg 1300ish with temp 79-80F and salinity 1.025. I don't dose anything supplements.

I ordered a bottle of NO-POX to bring the nitrates down with the thinking that I should get my tank balanced and stable before I order more coral in a couple of months.

Any thoughts on this approach? Am I barking up the wrong tree?

n4s · Aug 20, 2017

I had the same problem. I dosed Po4 which in turn brought down my nitrates from 25 down to 5 and brought my Po4 from 0 to .03
Coral color and growth improved drastically.

Randy Holmes-Farley · Aug 20, 2017

While I'm not sure it is the issue, it's a fine experiment to dose a little phosphate and see if it helps.

The elevated nitrate itself isn't likely the problem (assuming the measurements are accurate), but inadequate phosphate possibly could be.

Do you use tap water to replace evaporated water?

alyee5 · Aug 20, 2017

n4s said:
I had the same problem. I dosed Po4 which in turn brought down my nitrates from 25 down to 5 and brought my Po4 from 0 to .03
Coral color and growth improved drastically.

I haven't researched the adding PO4 part of the equation...what did you use to dose PO4? thx

alyee5 · Aug 20, 2017

Randy Holmes-Farley said:
While I'm not sure it is the issue, it's a fine experiment to dose a little phosphate and see if it helps.

The elevated nitrate itself isn't likely the problem (assuming the measurements are accurate), but inadequate phosphate possibly could be.

Do you use tap water to replace evaporated water?

I have a BRS 5 stage RO/DI system for my top off and FSW mixing...I maintain the DI resin fine...the inline TDS says zero FWIW.

Yes, I do like the problem solving aspect of the hobby and I am looking to choose one experiment for a month or 2 vs convoluting results with too many changes...

Are there distinct advantages/disadvantages of adding PO4 vs reducing NO3 to balancing?