[FitoPharmer]

I picked up a mixed zoa colony when I was down at the coast a few weeks ago. I started to notice a few days ago the polyps are not expanding as much as they were when I bought them, and they seems to be somewhat dulling. I expected the dulling because the light setup they were under previously would stimulate zooxanthellea far more then my old 150W. But the polyps seem to be shrinking or shriveling somewhat which is worrying me. I checked out my water yesterday and today to see if it was cycling or anything and it seemed fine:

Ammonia: 0
NO3: 0
SG: 1.026
Temp: 26
Dkh: 7.3
Calcium: 390-400
Mg: 1350-1400

+10% water changes weekly

Right now I have only a few other corals in the tank but they seem happy, a small mushroom and 2 ricordia yuma. Before I had a acro, pavona, hydnophora, and pagoda coral that did well.

Off the top of my head the possible causes could be:
1. No fish or food is in the tank. The tank was in a fallow period and I have not yet added back any fish. There is very little food going into the system right now. A pinch or 2 twice a week.
2. Pod city. I have read they can be harassed by pods, and my tank is packed full, again due to the fallow period.
3. Cyanobacteria. I was not changing my filter socks enough, now that I have switched to changing ever 2-3 days the front glass is going back to green algae from red.
4. Foam background/spray paint. Could possibly be leaching into the water.
5. Sickness of some kind?

Any suggestion would be awesome and greatly appreciated. I am really worried though zoas and I have never done well historically. In my last setup they always seemed to dwindle away.