I just bought a house with an in-ground pool and am trying to replace its 3HP single speed pump with a more efficient variable speed pump. I've done some research but can't seem to figure out what size pump I really need. My pool is ~10,000 gallons. It has a solar heating system that is on the roof of the house and an in-floor cleaning system. The pump and filter are downhill from the pool itself. I appreciate any advice!