My 14" Intex sand filter is beginning to spit sand into the pool. I don't really want to just repair or replace it with another Intex, so I'm thinking about a "real" pump/filter combo. The pool is only about 4500 gallons, so I probably need the smallest pump available, a two speed might be nice. I might also consider keeping the pump until it dies and only replace the filter for now. The system I have now is Intex model SF70110. Specs are - 120 VAC, 4.8 A, 30 psi max working pressure, 2150 gph max flow rate, 77 lbs silica sand.

I am well aware that some "engineering" will be necessary to convert from Intex proprietary fittings. I am capable and willing.

1. Should I really consider replacing the filter only?
2. What size and brand?
3. Is a 2-speed pump worth the extra cost on a system that small?
4. Other considerations I haven't thought of?