LPS recede and shrink!!!!!!!

[mandarin man]

Hi all,

I am just wondering if anyone experience a similar situation as I do. My LPS coral fully expand nicely after three to six after the photoperiod (when the lights are on). However, toward the end of the day some of the LPS tend shrink up and recede one or two hrs before the lights go out. My photoperiod is 8.5 hrs with T5.

I guess is that the coral cell (Zooxanthella) saturated with light or the lights are too intense. Is this normal? Your inputs are welcome.

Thanks