Battery backup or UPS?

[rsisvixen]

I use an inverter and a spare car battery, will run my big powerheads for 24 hours, I also got some small 2 watt powerheads and those will last 48 hours and up-not timed it yet.
Heaters need a lot of power, think you would need a generator if you want to run that for 24 hours, bylaws here mean I can't run a generator from 10pm to 8am, which is when the power outs seem to happen.