Can too much GFO lead to higher nitrates (4.0 ppm)?

[easperhe]

All,

For many months, my phosphates measured about 0.08 ppm on red sea test kit and my nitrates were 0.00 ppm. Since I had some GHA, I decided to get very serious about replacing GFO, increased skimming, etc to remove excess phosphates.

But in the last couple months, my nitrates have started to measure higher (2-4 ppm) and my SPS coral is starting to look very unhappy (browning, lack of polyp extension, less color etc). Any the Chaeto in my refugium has stopped growing. I got a Hanna Phosphate checker about a month ago to double check phosphate levels. The Hanna Phosphate checker consistently measures 0.00 ppm phosphate. So now I think that maybe the red sea test kit has always been off all along (saying 0.08 ppm when it was really 0.00 ppm).

Could the elevated nitrates and lack of Chaeto growth be due to there being a LACK of phosphates (from too much GFO)? If GFO is taking all phosphates out of the water, can that limit Chaeto growth and thus prevent the exporting of nitrates?

[toky916]

Our tanks do good with some phosphate. too much GFO can and will **** your corals off.
They need nutrition I feed a empty tank twice a week.
I only have coral sps never been happer I don't chase the phosphate anymore after reading a few articles.

[toky916]

http://www.advancedaquarist.com/blog/finding-the-right-balance-of-nutrients-for-corals

[greenhead]

X2 I battle too little po4 all the time. I hate the look of my pastel sps right now. Seems my perfect area is .04 on the po4. Nitrate can be anywhere from 5 to 0 and the sps don't seem to care. But strip the phosphate and your coral will die.

[SWBeginer]

NO GFO. Or only use 1/3 to 1/4 of the amount suggested.

[easperhe]

All,

I wanted to follow up on this topic. After stopping my GFO, my nitrates have indeed gone DOWN. PO4 is still reading 0 and NO3 is down from 4.0 ppm to .25ppm. As the redfield ratio would have you expect, having no PO4 is preventing my chaeto from absorbing any nutrients (PO4 or NO3).

But what is even more surprising to me is that my green hair algae (GHA) has disappeared!! After a month of no GFO or Carbon, the GHA is entirely gone - no trace that I can find!!

I'm not exactly sure why the GHA has gone away. I would have thought it too would require both PO4 and NO3 to live. I guess the GHA can live on NO3 alone?

Anyway, I just wanted to document for others the beneficial impact of not over doing the GFO. If you have high PO4 (using an accurate test kit), GFO makes sense. But, I was over doing it to the detriment of my tank.

[bimmer88]

if you're carbon dosing, too much gfo can lead to higher nitrates... carbon dosing involves the growth of bacteria, which require both nitrate and phosphate to grow. These bacteria are then skimmed out through the skimmer. If phosphate is too low, the bacteria won't grow, therefore not taking up any nitrates.