What can cause Hammar Polyps to "thin"?

[Singspot]

Hi There, check out ky video, my 2 Hammars (out of 10) have theor Polyps "thinning". They are both growing very well and happy but for last 3 weekz i have noticed the 2 Hammars (yellow and the lilac/ bleeched looking Hammar) are becoming thinner. ..

My water params
Phosphate 8
Nitrate 10
Alk 8.3
Temperature spiked yo 82.8 F for a couple of days but are fine now between 77 and 79

 

[blaxsun]

Hammers are LPS.