Word to the wise: Don't trust you reef tank to cheap heaters. Several weeks ago one of my 3 heaters cracked open during the night and my tank didn't like it. The temprature wasn't a problem due to the other two heaters being on still. The problem, from what I can tell, is the metals used in the heating element. The guts of the heater were in open water for about 8 hours. The reaction to this was that my tank was a white cloud of stinking death. Every acro and all but 2 stonies died (remember this was just from 8 hours of exposure). Everything else lived including all the fish...
So, now that the dead coral has been taken out and the heaters replaced (with 2 Ebo Jager heaters) I'm back in business.
Lesson learned: If you don't already use a high quality heater(s) and you value your livestock then you'd better get one. From my research (after the crash) the most reputable are Ebo Jager and Pro-heat Titaniums. The real stupid thing about this story is that the three cheap heaters I was using cost more than the two quality Ebo Jager heaters I replaced them with ($17.69 each from http://www.marinedepot.com )
Here is a picuture of the carnage the day it happend:
