Hmmm! I wonder sometimes!?

[mws]

I got this from nano-reef forum.
Just hopping Niger trigger and copper-banded butterfly wasn't a full size fishes.

Last night when I flipped on the lights to my tank, and I was shocked to find everything in my tank, all my fish, my brittle star, everything dead. I've had it up and running for about 2 years now, and lately been having problems with an uncontrollable infestation of aiptasia. I am at a total loss as to what happened. One suspect would be that our power went out for a couple of hours while I was out, but this shouldn't be enough to kill everything should it? With everything dead (except the aiptasia of course, which is flourishing), I plan to take the tank down, but am a little concerned. Having everything die so quickly, are there any health hazards I should be aware of for my own safety when cleaning it? Any ideas on what might have happend? Here is my setup

33 gal tank
Fluval 304 filter
2x96W compact fluorescents
2 Hagan powerheads
40lbs liverock

niger trigger
copper-banded butterfly
2 chromis
2 yellow-tailed damsels
1 perc clown
1 green brittle star
1 moonstone