Looks like classic dinos choking your corals. Dinos aren't just on the surface, they'll also in the water column. In my experience, they slowly kill everything. Any idea what you PH is? If dinos, the new silicates in the water change is believed to feed the dinos. One thing I noticed when I went through the horrible dino battle was that the water, itself, had kind of a rotten smell to it. If that's what you're dealing with, search on this site and on RC for how to manage them.