Switched to BRS GFO--PO4 Dropping Too Fast for LPS?

[daddy2kids]

I recently switched to BRS GFO (from PhosLock) and my phosphates dropped from 0.261 ppm to 0.067 ppm in less than a week (measured with Hanna Phosphorus Meter). Is this too fast for LPS? One of my acans is darkening a little and not puffy any more.

My phosphates had always measured around 0.2 ppm, which seemed fine for my tank. I have a bunch of softies--zoos, favia, acans, etc. (full list is below), which did great, and my chaeto seemed to out-compete most algaes (I rarely have to scrape my glass of anything except coralline).

I have never looked at SPS, and I'm really not interested in zero PO4 if it means I lose all my awesome softies.

Phosphorus and PO4:
3/21 71 ppb 0.218 ppm
3/24 77 ppb 0.236 ppm
3/31 85 ppb 0.261 ppm
Added 10 Tblsp BRS GFO on 3/31
4/1 50 ppb 0.153 ppm
4/3 37 ppb 0.113 ppm
4/5 22 ppb 0.067 ppm

Is this too fast for LPS? Do I need to back off? At this rate, I will be at zero PO4 in a week.

Thanks everyone!
Sean

 

[greech]

GFO can definitely have this affect on corals. Did you use more than suggested? Do you know what you alkalinity was before and after you started the GFO?

I have a lot of fleshy LPS and now only run GFO for a couple of days a month tops and I am actually using less than the recommended amount.

 

[daddy2kids]

Thanks Graham. Alkalinity before and after was around 3.5 mEq/L. I've had a good 2-part routine going for about a year. I used the suggested amount of BRS GFO, ~10 Tbls for my tank. I had been using 6 Tbls of PhosLock twice a month, so this fast slam down on PO4 took me completely by surprise.