my ups is on my tank and it runs 2x 3000lph sump pumps and a 300w heater. it ran my tank for nearly 1 hr last power cut but i have no idea how much the heater came on if at all.
i love my ups and it gives me peace of mind when im not there in the even of a powercut.
my next step is a little genny but the ups gives you time to get it up and running and it also comes on the instant the power goes off with out haveing to flip switches or run about like a headless chicken. i sometimes get home from work and if i hear the tell tale beep evey 30 seconds or so i know the ups has done its job threw the day while ive been at work.
a genny wont start its self up if no one`s there!, unless youve got big money to splash about on a proper set up.