Yellow polyp zoas turning brown

This colony is slowly starting to look worst and worst. The stalk gets skinnier and skinnier, and the head seems to bulg all water params are perfect, had my test backed up by lfs. Sg is 1.023 should I raise? Lights are 4 54 watt t5 2 are 10k and 2 are actinic+ I run my lights around 10 hrs. Should I be spot feeding or something? I have marine snow but have not been using it because of mixed reviews. This coral is in medium flow, about 12" from lights.










Before

After

 

SG is ok at 1.023 but better at or around 1.025. How long have you have the polyps? What are the other levels in your tank? PH, ALK, Ammonia, nitite,nitrates and temp? They may be too close to the light. They don't need strong lighting so maybe move them down towards the sandbed and see if they do better.

 

Ph is 8.2
Ammonia nitrate and nitrites are all 0

Ca is 380-400

Alk is 10

 

Is there anything in the tank or nearby that might be irritating them?

 

There was a bi color angel that used to nip at it but it was removed last week,

What could the shrinking darkening stalk mean?

 

I'm sure the bi-color angel was stressing it out quite a bit if it was nipping at it. It could also be your lighting as I said above. How long have you had them? If the LFS you got them from had them under less lighting and/or towards the bottom of their tank, they may be getting to much light. Move them towards the bottom and give them a few days or a week and see how they respond. Those polyps are very hardy and usually do great under normal h20 conditions.

 

I have some on a rock that is near the top of my stack and under 4X54W T5HO and they will not grow on top of the rock. They are doing great on the side and lower.

+1 on lower placement

 

Moved about 4" lower. Think it's enough? Or should input on sand bed?

 

probubly a little lower like 3 more inches

 

I would keep them within the bottom 4" of you tank 2" or 3" off the bandbed.