Assuming your overflow is set up properly to not flood your house in the event of a power failure, putting your sump on the backup power supply would be completely unnecessary. The only neessities you should put on the backup would be your heater(assuming it is in your main tank, if not, you could move it to the main tank during the outage), an airstone, and a couple of powerheads in the main tank for water movement. The point is to provide temporary power to the absolute essentials, not completely power your tank during the outage. Filtration will be fine to shut down for a few hours until the power comes back on, and lighting is fine to be off for a day or two, so that should also not be an issue. If you live in an area that would get power outages that last more than 5-6 hours at a time, on a regular basis, then I would suggest skipping the APC BackUPS and get a good gasoline- or diesel-powered generator.