I was thinking about this scenario a bit more. For those of us with multiple enclosures, flexwatt heat tape on the bottom of the enclosures might be a good way to keep the tanks warm. First they can be connected in series. Second they draw reletively little power compaired to an aquarium heater. Third, using a light switch dimmer you can adjust the heat/temp as required making them even more efficient. Thus using a Tripplite on a set up of this nature may provide many hours of back up heat. I have not done the math in quite awhile. So when I get some free time I'll try to figure it out to see how long a couple different option may last. My tank heater and one pump would run for about 4hrs on 2 batteries.... And that is for my 375 gallon set up. Fairly large heater and huge pump...