Open brain keeps bleaching- Why?

[Fish R Cool]

In my two month old reef tank, I have a nice
sized Green Open Brain. He was fine for about 5
weeks,nice and plump! But lately he seems to
expell his algae on a regular basis usually
late in the evening before the lights go out.
Water testing indicates that all paramiters are
normal.Oh, My lighing is a JBJ pc (7 watts per
gallon). The tank is a 30 gallon Oceanic.
Seaclone skimmer. 25lbs of LR. Marineland 330
power filter with the bio-wheels removed.
All of the other Corals are doing fine. What
can cause this? Any suggestions.
PS the Brain is about 1/3 up of the sand bed.
I also have a sand bed of only 1 inch. Should
I increase this.
Thanks

 

[Carpentersreef]

Don't worry. The coral is expelling excess zooxanthellae. Almost all my corals have done it at one time or another.
My Kole tang will hang around and eat it as it comes out.

Mitch

 

[THE CRAB]

HELLO AAAAHHHHHH BLEACHING WHAT IS THE TEMP OF THE TANK #1 PROB IN BLEACHING IS TEM OVER 80 FOR LONG TIME