Corals Contracted to 35%ish

[Stand_Alone]

Hi All,

Wondering if I could get some input as to what is going on.

My tank is about 2 months old. 90 gal with 25gal sump. I have about 7-8 SPS pieces in my tank. Also one frogspawn. Over the past month, I've had great coloring up and polyp extension. Today, all the corals only opened to about 35% during the light on period. My frogspawn which opens to the size of a softball every day now is the size of a baseball.

Parameters last month:

Salinity: 1.025
Temp: 74.5
PH: 8.1
Ca: 450
Alk: 8
Mg: 1100

Salt mix is Red Sea Coral Pro salt. It mixes to those levels, which is way different than what the bucket states. Test kits are Elos.

Current parameters:

Salinity: 1.025
Temp: 74.5
PH: 8.1
Ca: 400
Alk: 8
Mg: 1000

I've been dosing a little mg to try to increase it but it's been marginal.

Any ideas what's going on? Or is this just something that corals do?

 

[layer3switchguy]

Wow, your temp is really low at 74.5 for SPS, plus the Mg is low as you noted. Either of those things could cause your issues.

Also, you mention the corals are only open about 35%, I assume with the exception of the frogspawn, you mean polyp extension?

 

[Stand_Alone]

Wow, your temp is really low at 74.5 for SPS, plus the Mg is low as you noted. Either of those things could cause your issues.

Also, you mention the corals are only open about 35%, I assume with the exception of the frogspawn, you mean polyp extension?

All the research I've read is that 74-75 for SPS is fine (I plan on keeping cooler water fish). And for the past month they seemed to do great in that temp range.

Yes, I meant to say that all corals seem to be 65% less polyp extension than normal.

I wouldn't be worried if it was just one coral but it's all of them. Just wondering if it's normal coral behavior or something is wrong. I can post pictures if it helps.

 

[layer3switchguy]

Lots of variables that could cause this.. Do anything new to the tank in the last few days?

 

[Msleckro]

Your Mg is low.. i'd raise it slowly. What is your phosphate levels?

 

[toothman]

acros do better at 78 degrees, mg is way off, acros also do not like quick change in mg, so raise it slow to 1290.

 

[Nemo4ev]

I think Mag could be a major problem. I increased my mag from 1100 to about 1350 and saw a big difference in my polyp extension

 

[Stand_Alone]

Thanks for the feedback guys. Regarding increasing mg, what do you guys recommend for product?

I've heard good things about BRS mg supplements..