We have a Pentair Variable Speed Pump which is awesome. It is set for:
1600 RPM for 6 hours at night for chlorination (salt water)
1100 RPM for 15 hours (just to keep the water filtering).
Off for 3 hours (5 pm to 8 pm peak electric costs).
At 1100 RPM it is 12 GPM using 80 watts.
At 1600 RPM it is 20 GPM using 200 watts.
In full California sun this is sufficient to keep it clear and clean.
I also need to add Acid about once a week to keep the PH down (due to the chlorine generator and water slide).