Do you really like the SeaApple that much ? ... it just wiped out the tank ! ... first of all they are a risky choice of tank inhabitant for just that reason and so you should not worry too much about the heater as that " bad " apple should be on it's way back to the LFS
. Not ragging on ya but did the LFS warn you two about the risks of keeping a SeaApple ?
If you do a search for reef-safe critters there should be lots of reading for you on what is reef-safe and also what poses potential risks to tank inhabitants.
Cheers