Where did my polyps go???

I hatve an ora Joe the Coral that has been doing great and the last few days. It seems that something is eating the polyps. I do not know what is going on. The 1st pic is from about a week ago and the other 2 pics are from today. You can see that almost all of the polyps are gone. I have about a dozen other sps corals that are doing great this is the only coral affected.
Recent water params as of yesterday.
ph 7.9-8.1
sal 1.026
nitrate 10
phos .2
cal 450
alk 9.8
mag 1325

 

there not actually gone they have receded into the tubes. sometimes my rosa milli does this. also check at night and see if they come out after the lights are out.

 

I have checked at night and they do not come out at all. It also seems to be losing its color.

 

It looks to me like you have good growth and the color change appears to be from good lighting. If it goes white, (bleaching) then that is a problem. Just keep track of it and see what it does. Maybe you will find a culprit. Watch your other corals to see if they are getting attacked.

 

Lighting in the tank has stayed the same. The only fish that I see hanging around the coral and also seems to be nipping at it sometimes is my 6 line.