personally i have a apc xps 1200.. i think the model number is bv1200 or somthign liek that.. my mag pump is a piece of ---- and any power hiccup at all and it stops pumping and wont resume.. i have to pull it out of the water for it to start.. it dumb.. anyway i've got three PH hooked up to it and on my test run it lasted for over an hour. Its really up to you how long you want it to last.. it comin up on hurricane season now so im actually considering buying another