http://www.aquabird.com.vn/forums/showthread.php?t=4098
The guy had a power failure for only 10 hours when he was away at work. Apparently, his backup power supply only lasted 4 hours.
So, I think that for any of us with a lot invested in discus should seriously invest in battery back up systems that will kick in automatically. Hopefully, this will hold out until you get home or until you get notified so that you can turn the generator on.