Ok, think I've figured it out. I had one of my returns a few inches away from the back side of this coral and it was blasting away the thin green layer over the coral. The white stuff was the green stuff bunching up and flaking away. I've fixed the direction of the return and it kind of looks like algae is starting to grow on the now white sections.

What I'm doing, waiting to see if the white creeps forward and a small amount of praying that it doesn't.

Question is will it continue? Will the green stuff grow back? The polyps are still coming out and the rest of the coral appears to be fine. I'm standing by with glue and live rock rubble in the event I have to frag out the colony to save it.

I have two rocks with a frag mounted, encrusting, and growing on my rack. One belongs to ScuboSteveo. This tells me that at least in the case of this particular area my fragging skills are up to par in case I have to cut out the dead area of the coral.

Gonna get Milly to snap a few pics.

Advice?