With me, Tissue Necrosis happens when any number of things get out of whack. You could probably write papers and do research on any number of them as a cause, but not the cause. New tanks, media driving available N and P too low are the two biggest causes that I see with tissue necrosis.
Healthy corals seem to be able to withstand more stressors, but this is all subjective. This is one reason that I keep my water parameters near NSW, keep them stable and use the best lighting that I can to feed the corals and I keep a high throughput of building blocks without high residual levels. I have had events in the last year where my alk dropped to 4.0 and then back up to 7.0 in a few minutes with some baking soda, temp down to 65, had some electrical current from an old/bad pump - everything was fine. I will say that my stuff grows fast and I feel that I provide the best homes for them possible.
I would focus on things that keep them as healthy as possible and not worry so much about the bad things... it all works out when you do this.
Healthy corals seem to be able to withstand more stressors, but this is all subjective. This is one reason that I keep my water parameters near NSW, keep them stable and use the best lighting that I can to feed the corals and I keep a high throughput of building blocks without high residual levels. I have had events in the last year where my alk dropped to 4.0 and then back up to 7.0 in a few minutes with some baking soda, temp down to 65, had some electrical current from an old/bad pump - everything was fine. I will say that my stuff grows fast and I feel that I provide the best homes for them possible.
I would focus on things that keep them as healthy as possible and not worry so much about the bad things... it all works out when you do this.