Help Zoos Shrinking

[hannan]

I have 6 colonies of zoos each one was brought at a different time and some from same place some not. Every colony is fine for about a week and then they decline slowly. All water parameters excellent.
Tank Size: 54 gallons
spg: 1.025
temp: 78f
amonia: 0ppm
nitrite: 0
nitrate near: 0 5-10 max
calcium: 360 maybe a little low
phosphate: 0
dkh: 9
good water movement
lighting: 250w mh 14k 8 hours daily
two 65w actinics 3 hours daily after halide turns off
dose: 1-2 drops lugols weekly
also I've tested for copper 0ppm
other corals: toadstool, wells open brain, tounge, hammer, sun coral, sea fan, xenia and 2 sps. lps and sps corals doing fine, xenia is also shrinking. The only Zoanthid thats doing well seems to be the yellow polyps.
fish: 2 damsels, watchman gobby and alge blenny.
Any ideas would be greatly appreciated. Thanks, Chris

 

[ct_vol]

Do they ever open up and look healthy??? Or are the polyps always slightly closed??? Do you do any light acclimation???

Do the mats recede or do they polyps pinch off at the top???

Pictures always help... Good luck...