Whats happening to my corals?

[Chad]

I've read this many times and seen it a few, so I will try and explain from my limited experience.

When an acro / sps starts to RTN, often it becomes a tank event. With no real explination. Your best course of action is to frag the RTN'ing coral as soon as you notice and get the dieing tissue out of the tank. Also you want to frag deep into good tissue, not just at the edge of the RTN.

So, perhaps one coral RTN'd in the begining, and now has cause the tank wide event.

Just my 2 cents.