Whats going on with my zoas

[lpd154]

I need some help figuring out what is going on with my radioactive dragon eye zoas. Recently some of these zoas have lost their color and seem to be withering away. They still open and close but just seem to be on deaths door step. I have included some pictures so that hopefully someone will have an idea of what is going on and maybe have some ides to keep me from losing the whole colony.
These zoas have been kept under a 300 watts of metal halide in a 55 gallon rectangular tank that is 20 inches deep with the top portion of the zoa colony about 10 inches below the light source.
My perimeters are:
Alk: 125.3
Ammonia: 0
Calcium: 480
Kh: 7
Nitrite: 0
Phosphate:0
Salinity: 1.0215
Nitrates: <5
Ph: 8.4
Temp: 80
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[mrdc]

Are you saying the ones at the bottom used to be green like the ones in the top picture? The bottom ones look so much like brown button polyps but I am not the best identifier.

 

[lpd154]

Yes they were all green and initially part of the original colonly, the ones that you see on the bottom broke loose from the colony and settled on the rock. If you look at the very top of the colony there are several of the polyps that look just like the ones you see on the rock. I just couldn't get a good picture because of the angle. These all started off just alike and now some seem to be getting sickly or dying.

 

[speg]

How long have you had them until they started this problem?

 

[lpd154]

I had gotten them about 3 or 4 weeks prior to noticing this problem, and it was a gradually onset. I just wish I hadn't changed lighting systems in the middle of this problem appearing, at least then I could include or exclude lighting as a contributor to the problem.

 

[mattyp75]

The second picture is almost definitely a different critter. I got a rock of the orange and green a couple months ago. It looks like it's the same stuff. I got it home and noticed a few button polyps were also attached to the same rock. So, you've ended up with 3 corals. The button polyps will have longer stalks and long, thin tentacles. They've been outgrowing the zoa's so far but aren't stinging them.