Mammoth,
Congrats on your TOTM, and very sorry to hear about your issues here of late. Do you think it was the heater causing the issue?
You know, one thing I notice once in a while with otherwise very healthy SPS systems is an RTN/STN event like what you had, which I experienced myself as well in a 300 gallon a couple years ago. One characteristic of many of these events is that the tank is very mature with large colonies and a lot of different species of SPS.
I have always wondered if these colonies have become so large, with such a great amount of allelopathy between the corals, in such a limited amount of water that is in a reef tank compared to the ocean, that it triggers an event like this? Kind of like the water reaches a critical mass in the stuff coming of the corals, maybe more than can be handled by traditional methods of reef filtration.
I could not find a definitive cause of the meltdown I had in my 300 gallon. I have just noticed this happening once in a while in mature SPS reefs with a wide variety of acros.