Detective work

I'd like to find out what happened to my tank to hopefully avoid it in the future. Combing the internet has been of no great help, so I figured you guys could.
About a month ago I fed my fish in St. Pete and left for Tampa like I always did. I returned two days later to be greeted by a powerful stench had consumed my room. I immediately looked to my tank and, to my horror, found that the water was an opaque green. I desperately attempted to find if any of my fish were still alive, only finding carcasses. Most had sunk to the bottom, only one was floating. All of my filters were running and all of the fish were whole (not nibbled even a little). In my years caring for fish I had never run into something like this and I have no idea what could have caused it.
I can answer any questions any of you have if it will help find out what happened

Hmm...definitely weird.

I've got a few ideas...

- Power outtage while you were gone. This could have led to a depletion of oxygen killing everything.

- Temperature swing. Did the temp change a lot while you were gone?

- Stray Electricity. Maybe one of your electrical devices broke or started producing stray voltage in the tank...?

That's all I've got...

All of the filters were running when it got to the tank that day (and completely filthy). The temperature swing theory is the best I have to work with at the moment. I have a heater that will be set to prevent any dramatic drops in temperature. I just really hope that it never happens again.

id have to agree with temp swing theory