A variable-speed pump saves energy because power use drops sharply as speed drops, so running longer at low speed moves the same water for far less electricity. Size it to turn your pool over in about 6 to 8 hours, keep flow within your filter's rating, and match voltage and plumbing size. In the US, federal efficiency rules mean most replacement in-ground filtration pumps are now variable speed.
The pump is the heart of the pool and its biggest electricity user. A variable-speed pump is usually the fastest-paying upgrade a pool owner can make.
Why slower saves
Pump physics: flow rises in proportion to speed, but power rises roughly with the cube of speed. Halving speed halves flow but cuts power to around one-eighth. Run longer at low speed and you move the same water for a fraction of the energy.
Sizing for turnover
Turnover is the time to circulate the full volume once.
Flow needed (gpm) = gallons ÷ (turnover hours × 60).
| Pool | 8-hour turnover |
|---|---|
| 15,000 gal | 31 gpm |
| 20,000 gal | 42 gpm |
| 30,000 gal | 63 gpm |
Calculate your volume with our pool gallons guide.
What else to check
| Check | Why |
|---|---|
| Filter’s rated flow | Pump must not exceed it at high speed |
| Voltage (115 or 230 V) | Must match your circuit |
| Plumbing size | 1.5 or 2 inch lines change flow and resistance |
| Total horsepower or THP | Compare like for like |
| Automation compatibility | Some pumps talk to controllers |
| Above-ground or in-ground | Self-priming in-ground pumps vs above-ground models |
Settings that work
- Low speed for most of the day for filtration.
- Higher speed for an hour or two for skimming, vacuuming, heating or salt cell flow.
- Check the heater and salt cell minimum flow requirements.
Pair the pump with the right filter. Browse pumps and filters.
Common questions
Do variable-speed pool pumps really save money?
Yes. Pump power falls roughly with the cube of speed, so half speed uses far less than half the power. Savings depend on your hours and rates.
How long should I run my pool pump?
Long enough to turn the water over at least once a day, often 8 to 12 hours at low speed, plus short high-speed periods for cleaning or heating.
What size pump do I need?
Enough to turn your pool over in about 6 to 8 hours at a speed that stays within your filter's rated flow.
Can I install a pool pump myself?
Plumbing is doable for some owners, but wiring should be done by a licensed electrician to local code.