Replace old inefficient pump with new more efficient pump

[Watermom]

A sand filter will have to be backwashed several times each season, and will dump 200 - 300 gallons of dirty -- maybe greenish -- water SOMEWHERE, each time.

HUH?? When I backwash my sand filter, I would guess I lose no more than 50 gallons (high estimate) of water each time. I usually backwash for a minute or maybe a minute and a half.