Bigger pool pumps waste money.

No, you probably need a smaller pump than you think.

Most people oversize their pool pump. The rule of thumb is to turn over your pool’s volume once every 8-12 hours. Calculate your pool gallons (length x width x average depth x 7.5 for a rectangle) and divide by 480 (8 hours in minutes) to get the minimum flow rate in gallons per minute (GPM). Then add a little for head pressure (friction from pipes, fittings, filters) — maybe 10-20% extra.

A bigger pump pushes more water faster, sure, but it also costs more to buy, uses more electricity, and can actually reduce filtration efficiency (water passes through the filter too quickly). A properly sized pump runs longer but uses less peak power. Variable-speed pumps are even better — they let you run low for filtration, high for cleaning.

I’d start by checking your filter’s maximum flow rate. Pump bigger than that is pointless. If you have a sand filter, even more so. And don’t let a pool store sell you a 3 HP monster for a 15,000 gallon pool. That’s like putting a Hemi in a Prius.