Zoa colony sick

[paragrouper]

The tank is 32 gallons.
Parameters are

Ph: 8.1
Temp: 77.1 F
S.g: 1024
phos: .18
Nitrate: 11
Alk: 8.6
Cal: 420
mag: 1280

The issue is with a single colony that has been in the tank for about 7 months. The picture below is what it normally looks like. (Blue with orange skirts, above the blasto.)

It has been like this for the last 4 days. As you can see, most of the polyps are closed up and some appear to be turning brown. And help or advice is appreciated.

 

[BasementBox]

Seems to me that it’s not just that, the coral in front of it is retracted too.

 

[paragrouper]

Seems to me that it’s not just that, the coral in front of it is retracted too.

To the naked eye no. I turned up my whites as much as I could for the photo. The other Zoa colonies, and all other corals look normal.