whats going on?

[PL-Reef]

i bought this arco a month or so ago, and i noticed that it had so parts of the tissue missing between the polops. the arco is getting great PE. well slowly the bleaching (?) is getting worse. do any of you know whats going on?
ids welcome.

 

[beeker]

well i wish i could help but i have honestly not seen anything like that unless it's AEFW or ref bugs.

 

[PL-Reef]

any ideas?