Bottom up STN

[OregonReefer2]

I'm having trouble with some of my SPS. Many are going great but a few pieces not so great.

8x54w TEK Elite pushes 250 par at the sandbed and almost 400 on top of the rocks

120g DT / ~150 total volume
Salinity 1.025 (refractometer)
alkalinity 9.5 (Hanna)
calcium 440 (Red Sea Pro)
magnesium 1420 (Red Sea Pro)
temp 78-79.5 (Apex)
nitrate 0 (API) confirmed at LFS
PO4 .00-.03 (Hanna)

I dose BRS 2-part with dosers to hold cal and alk levels.

I was running GFO but after this problem started I stopped. It seems the Fuge/chaeto is holding the PO4 down on its own.

I'm at a loss here and hoping for some help from the gurus

 

[sahin]

Your parameters all seem fine and within acceptable range. Was the STN there BEFORE you used the GFO?

If not, then perhaps you used too much or that the phosphate reduction was aggressive?

Dont resume the GFO use until corals have started to recover, and only use 1/4 of the amount you currently used. And only use it if the levels start going above 0.04ppm.

Let us know in a few days how things are going.

Are you doing any form of organic carbon dosing btw?

 

[OregonReefer2]

I had been using BRS HC GFO for a long time before the STN started. I was using about 1/2 a cup per week in a BRS deluxe reactor.

With the mostly .00 readings on the Hanna I decided to take the GFO off line in the hope I was running a little too UNLS. After a week of heaver feeding my PO4 reading is up to .02 (with Hanna margin of error that's .00-.06)

The only algae issue I have is a little cyno tends to grow in the fuge but I think that's more a lighting issue

And, no, I'm not doing any organic dosing

 

[mos90]

its so hard to determine what actually causes an stn event. so many variables.

a few things i personally would do.

1) like sahin said remove gfo. .04 is a good # to max out at. only use 1/4 cup of high cap gfo. im only using 1/2 cup in my 350g and i have a high bioload.

2) from my experience as a system gets lower in nutrients higher alkalinity levels seem to cause problems. i like to shoot for 8-8.5 dkh. some will say 9.5 is fine and it may be.

3) target feed coral specific food. a few times a week.

4) be careful not to raise po4 too much. the goal is to slightly increase nutrients, not raise it so high you need to put gfo back online next week.

 

[sahin]

Nothing seems out of the ordinary...

Have you verified the Salinity with someone else/LFS?

 

[OregonReefer2]

I've taken the ALK doser off line. My salt mixes at 9 so I'll let it drop to that and see what happens

I just checked the refractometer with calibration solution and it's right on.

 

[powder_blue]

I've had this issue with a few maricultured corals. Especially Millie's. I fragged them about 1/2 in above the tissue loss and have had great success. All my params were in line as well. I think sometimes things just happen. I let one go without fragging and lost it. I run gfo as well and have wondered if it was the root but which is worse the effects of gfo or having high phosphates. I've stuck it out and kept doing the same and everything is doing great.