A friend of mine has a Intex 15' x 40' x 48" oval pool, with the pump/cartridge filter that was sold with the pool. In answering questions for him about upgrading to a sand filter, he's decided to do so. He is not able to tell me anything about the pump itself other than it's an Intex model 8111, which, in looking at the Intex site, almost appears to be a SWCG system? Since matching pumps and filters is NOT my forte, what is a reasonable (read: efficient) pump/filter combination for this pool?

Janet