I just got a battery-powered air pump from Drs. Foster and Smith in an order yesterday in case of hurricanes. We had the power out for several days on a few occasions (Charley, Frances and Jeanne) last year, but didn't have an aquarium then. I figure the important thing to do is to keep the water oxygenated for the fish and bacteria, and that means water movement. A battery powered air pump and stone seem to be the best way to do that. Losing the power filter for a few days is probably not going to hurt much as long as I do a daily or bi-daily (is that a word?) partial water change and vacuum the feces and uneaten food off the gravel. With no water motion through my power filter, I would expect to lose much of the bacteria in the bacteria spongy thingy in there, but there should be plenty on the other surfaces in the tank.
Some people are concerned about keeping their tanks warm without power, but if you're in a hurricane-prone place in hurricane season like we are, a bigger concern is keeping the aquarium cool . I've just decided that there's not much I can do about that and hope for the best.
When I move my tank to my yet-to-built new stand, I'm tempted to put in an undergravel filter for just such cases - it's not to replace my regular filter, but to be there in the case of a power outage.
BTW, I got the Hagen air pump - about $8. It works, but I'm not too impressed with the overall construction, but what did I expect for that price? I wonder how it compares to the cheaper AZOO models. A coworker has a Penn-Plax that she bought locally, but I didn't look closely at it.
