ups and motor load

Electrical Help - What size/type) or brand UPS would give me about 15min run time for a 110w pump (rated 2.48a)? The pump is a Quiet One 5000. I tried a 550va (330W) APC UPS and it overloads. I then tried a smaller pump on the same UPS and it will also overload. I tried a resistive aquarium...