Whats wrong with my fox coral

[hossa81]

So quick story i had a small fox coral. It was doing good for a while but then half of it started shrinking and i think its dying. The oter half of it is still doing good.
It is on the bottom of my 20 high. I have two twenty four watt t5 ho bulbs. One 420 actinic and one 12000k daylight bulb
My parameters are:
Nitrite and ammonia:0
Nitrate at fourty
Ph is 8.4
Temperature is inbetween 78-80

 

[tektite]

Have you ever dipped it to see if it has pests on it?

 

[hossa81]

Have you ever dipped it to see if it has pests on it?

Have dipped for five minutes using coral rx once.