buuble coral not opening anymore

[swansongofzoso]

Ive had a big pearl bubble coral for over 2 weeks now and it was doing awsome for awhile, as of late the upper half of the bubbles havent really been coming out. I have it high up in the tank, is it possible its gettign too much light? Ive also been useing some az no3 to get my nitrates down alittle, so i dont knwo if that could hae an impack on the bubble, but all the other corals are doing fine?
any ideas woudl be great thanks in advance

 

[swansongofzoso]

the coral is about 10 inches directly under a 150 mh and there is another 150 mh about a foot away