I am looking to get a new pool pump (or just pump motor). I want to go with a 2 speed pump and have found a replaceable motor. But am not sure that is pump was not oversized from the beginning.
Some Background: This is what I currently have; an above ground about 16x32 oval (close to that, can not remember the exact measurements) about 13,000 gallons. Currently I have a Hayward sp -1575x1? (the zero might have faded off sp 1575x10) it is a magnetek 1 HP 115 volt 12Amp 3450 RPM motor, A hayward S160T sand filter, with 150# sand, an aquarite SWG and then a Jandy LX250 btu heater. It is 1.5 inch PVC. There is about 6 feet of PVC to pump, then 5 feet of PVC from filter through aquarite to heater and the 8 ft PVC back to pool. All PVC is almost on the same height off of the ground. Currently the motor is wired into a 3-way switch to control the motor from both the inside and outside the fence. Running off of a 20amp GFI circuit.

Question: I want to get a 2 speed pump was not sure about the size to get. I could the same size, but have read about how pumps are always oversized. So is this motor oversized for my pool? Also should I just get the motor, or for about 2 times the money get the whole pump? Right now the only thing that is wrong the current pump part is that there is a very small drip from the threaded in input line (I over tightened it at one point) It does not even leak all of the time.
This was my plan to get a just another motor same size, just 2 speed, and keep the pump part with new seals.
Any help/insight would be great. Thanks