[ScubaSteve]

Ah crap dude! That really sucks.

If it was the halide that caused it, there could be a couple things going on (just going to toss some ideas out there). Metal halides use mercury vapor and some keep a small mercury pellet inside to keep the vapor pressure up; may e that got I to the tank. Is there something that hit the lamp and got fried (jumping fish, etc)? Re the bulbs SE or DE? Were they uncovered?

The coral behavior sounds like a chemical issue to me. Run tons of carbon and add an ammonia remover pad to battle the die off. I am suspicious of the maracyn.

Let me know if I can help you out at all.

Edit: sorry for the stupid iPhone autocorrects. Apparently the default language on my phone is illiterate hillbilly.