[untamed]

I have no proof of this... What I'm about to say is strictly my own opinion based on observation and personal theory..

I believe that there are naturally occuring bacteria that feed on dead/dying coral tissue. A crude analogy would be to compare these to what is called "Flesh eating disease" in our own bodies. They are going to be present in every aquarium and there is nothing you can do to eliminate their presence. Healthy coral has no problem with these bacteria, especially if the bacterial population is low and there is little decaying coral to feed on.

As system parameters change to unhealthy for coral (for many possible reasons), some coral becomes unable to defend itself and some of the tissue dies. This dead/dying tissue is food for this bacteria, leading to an increase in the bacteria population that feed on dead coral, putting more pressure on the remaining coral tissue and other coral in the tank.

A weakened coral can very quickly be overcome (RTN, STN), but the resulting bacteria population bloom can take out an entire tank in very short order.

Again, this is only my theory based on my personal observations of how RTN/STN events seem to unfold. This means that the best defence is to keep tank parameters in line as much as possible...and aggressively remove any dead/dying coral tissue from the system as quickly as possible.

When I see a coral that looks to be in trouble, I remove as much dead tissue as possible, and dip the remaining healthy portion in an iodine based dip (like TM Pro-coral cure). Carefully observe coral that is physically NEAR to a coral that is in trouble as these will be among to the first to show signs of trouble.

Anyway...that's my $.02 worth of opinion. Please be polite if you think I'm just a crackpot who doesn't know what I'm talking about.