I'm afraid so, even though I took the "+1 on the use of GFCI's."
(Like I think I mentioned, but not 100% sure anymore,) I seem to get about 1-2 nuisance trips per year. I call them nuisance trips because I'm never able to find the cause. I've posted about this in the past and was told "it's because something caused it to trip." But I can't find out what, and if it only happens every 6 to 12 months there's no hope of being able to find it. At least when I plug things back in, nothing trips it, and no stray voltage in tank using a multimeter. <Shrug> Maybe I diagnose incorrectly, I'll admit I'm no electrician. I try to understand, but some things are above my head.
Anyhow, sorry, to the point, last summer I had a GFCI trip, and Murphy's Law kicked in, nobody noticed until a good 8 or 9 hours later. Ordinarily, I load share my tanks between two circuits, so if one GFCI trips, the other still tends to run, and usually either the sump return pump or the powerheads stay on. Because of this I've had power out on one circuit for long periods of time before, and never lost anything before.
But my 20g was all on one circuit, it was such a low-cost-to-operate tank that I just had it on the 1 circuit and so the tank was completely flatlined for the 8-9 hours.
I lost a pair of flame angels. I found them wedged into crevasses in the rock, one was so badly rigored I had to break the rock to remove him. Beautiful little pair of Hawaiian red flames and they were getting along perfectly too.
I regret that I lost these fish. I don't know that I regret the GFCI though still. Maybe the solution is to use a controller or something that can give an alarm when power goes out. At the very least, one of those powerfail screamer nightlight things, but I haven't been able to find any locally (I admit I haven't looked as hard as I could have though)
Like this:
http://cgi.ebay.ca/PowerOUT-Power-Fa...3286.m20.l1116