Mushrooms bleaching

[MarlinHooker]

So what would cause this? I have purple, red & fuzzy green mushrooms & some of both the purple & red are bleaching out. The fuzzy seems unaffected. Tank parameters seem ok:
SG 1.026, Ca 500, Alk 8.0, Pho .1, Nirates 0, temp 78.

 

[Constantine]

Likely lighting, but I'm just regurgitating what I've read online. Too much or too little can change the number of zooxanthellae in the coral which changes the color.