Guide
How long to run a pool pump
Run the pump long enough to move the whole pool through the filter once a day. The turnover math, typical flow by pump size, hot-weather hours and what each speed costs.
Updated · 3 min read
Run your pump long enough to push the whole pool through the filter once a day. That is one turnover, and the hours depend on your volume and your pump's flow: a 15,000-gallon pool on a pump moving 40 gallons a minute needs about 6.3 hours. In hot weeks, run it up to a quarter longer.
If you only want your number, use the pump run-time planner. It works out the hours and the cost at each speed your pump has.
The turnover math
Hours for one turnover = pool volume in gallons ÷ flow in gallons a minute ÷ 60.
In metric, it's litres ÷ litres a minute ÷ 60: a 57,000-litre pool at 150 litres a minute takes about 6.3 hours.
| Pool volume | At 40 gpm | At 60 gpm | At 90 gpm |
|---|---|---|---|
| 10,000 gal | 4.2 h | 2.8 h | 1.9 h |
| 15,000 gal | 6.3 h | 4.2 h | 2.8 h |
| 20,000 gal | 8.3 h | 5.6 h | 3.7 h |
| 25,000 gal | 10.4 h | 6.9 h | 4.6 h |
Your pump's label or manual gives its flow, or its horsepower. If you only know the horsepower, these are typical full-speed flows; your pump's curve and plumbing change them.
| Pump size | Typical flow at full speed |
|---|---|
| ¾ HP | 55 gpm |
| 1 HP | 65 gpm |
| 1.5 HP | 90 gpm |
| 2 HP | 110 gpm |
| 2.5 HP | 130 gpm |
| 3 HP | 150 gpm |
Don't know your volume? The gallons guide shows how to measure it.
Hot weather
Run longer in a heat wave. The planner's rule: no change when the hottest day of the week is 60°F (16°C) or cooler, rising evenly to 25% more hours at 85°F (29°C) and hotter.
Slow and long costs less
Flow drops in step with pump speed, but power drops with the cube of speed. That's why a variable-speed pump running slowly for longer uses far less electricity than full speed for a short run.
An example: a 15,000-gallon pool on a 1.5 HP variable-speed pump that draws 1,500 W at full speed, with electricity at an example rate of $0.25/kWh.
| Speed | Hours a day | Power | Energy a day | Cost a month |
|---|---|---|---|---|
| 3,450 RPM (full) | 2.8 h | 1,500 W | 4.2 kWh | $31.50 |
| 1,500 RPM | 6.4 h | 123 W | 0.79 kWh | $5.92 |
Same turnover, 81% less electricity at the slow speed. The cube rule is an ideal estimate; real pumps save a little less because of the plumbing. In a week with a high of 85°F or more, the slow run grows to 8 hours.
How to set your pump schedule, step by step
- Know your volume. Everything else follows from it; use the pool volume calculator if you're not sure.
- Find your flow and power. The pump label lists horsepower, and often watts or amps (watts are amps × volts).
- Pick the slowest speed that still works. Your heater, salt cell and cleaner each need a minimum flow, so check those first.
- Set the timer for one turnover a day. Add time in hot weeks, after heavy swimming and after rain.
- Watch the water. If chlorine drops faster than usual or the water looks dull, add an hour a day.
Whenever you add chemicals, add each one separately, with the pump running, so it mixes before the next.
Questions people ask
Do I need to run my pool pump 24 hours a day?
No. Most pools need one turnover a day, usually 6 to 12 hours depending on speed. Run longer in heat waves, after heavy use, and around the clock while you're clearing a green pool.
Is it cheaper to run on low speed for longer?
Yes. Power falls with the cube of speed, so half speed uses about an eighth of the power for twice the time. In the example above, 1,500 RPM uses 81% less electricity than full speed for the same turnover.
Should I run the pump during the day or at night?
If electricity is cheaper overnight, run part of the schedule then. Keep the pump running when you add chemicals; chlorine is best added at dusk, so the sun doesn't burn it off before it has done its work.
What if I have a single-speed pump?
Run it for one turnover at full speed. The planner shows those hours, and what the same turnover would cost at slower speeds if you ever change pumps.