Coralline algae overgrowing corals

[Europhyllia]

You guys were right. Something else must have been ticking off my GSP yesterday evening. When they all hid away I inspected the rock and found the coralline and thought that was it but the stars came back out later that night.

Of course where they are overgrown they're not coming back. :( I have them in pretty good flow (intersection of two 1500 gph Seios) but I'll see if I kind find a higher flow area.