Bubble coral
 

I have 3 bubble corals in my tank and 2 of them are fully opened for the first 4h after the lights come and then they deflate (they may or may not inflate again before the lights turn off). It repeats itself everyday...I have noticed this phenomena happening only during the hot days. Can it be temperature related issue (aquarium temp goes up to 84 from 80)?

I feed my bubble once or twice a week...