i have 2 battery backup air pumps, because within living at my new house for 6 months my power has been off twice, once for 10 hours, once for 18 hours....
if you get a generator you would need a decent surge protector, because a generator produces a crude current, not a steady current that comes out of the wall, so if you didnt have a good surge protector you would probably fry all your pumps...atleast to the best of my knowladge, something to think about