Light acclimation.. One frag unhappy..

[Delphinus]

I concur with the mushroom damage theory (or some other kind of "territorial dispute"). No anemones near your SPS, right?

The few times I've seen bleaching caused by light shock, it was more of a systemic bleaching. It's kind of hard to describe, but basically each polyp would have a bit of bleaching and then each spot of bleaching would grow, until they all met, at which point there was nothing but skeleton. (In the time that I mentioned about where my halide bulb lost its casing, the burned acro was nothing but bare skeleton when I even noticed it. The lights hadn't been on for more than 2 hours. It was just dumb luck that I happened to be home for lunch that day. Otherwise it could have been another six hours before I got home and noticed something wrong. But ... that's another story!)

I think you're doing the right thing by observing closely. I would guess you're on the right track: if the polyps are extending just fine then presumably it must be OK with the new light. Good luck!