How pool pump run time works
A pool stays clean when the pump circulates the whole volume of water through the filter at least once a day. That is one turnover. Turnover time is pool gallons divided by the pump flow rate in gallons per minute. Run the pump for that long, and the water gets one full pass through the filter.
The cost question is where single-speed and variable-speed pumps split apart. A single-speed pump runs at one fixed high speed, so every run hour is expensive. A variable-speed pump can run on a low eco speed: it moves less water per minute and runs longer, but the power draw collapses because pump power scales with the cube of speed.
Why slower is cheaper
Pump affinity laws: flow scales with speed, but power scales with the cube of speed. Drop the pump to half speed and it moves half the water while drawing roughly one eighth the power. Even though it now runs twice as long to hit the same daily turnover, the total energy used is a fraction of the single-speed number. That is why a variable-speed pump on a long low-speed schedule is the cheapest way to keep a pool circulating.
Pool pump run time FAQ
How long should I run my pool pump each day?
Run the pump long enough to turn the water over at least once per day. Turnover time is pool volume divided by the pump flow rate. A 20,000 gallon pool with a 70 GPM single-speed pump needs about 4.8 hours for one turnover. A variable-speed pump on a low eco speed moves less water per minute, so it runs longer, but uses far less power.
What is a pool turnover?
A turnover is the time it takes the pump to circulate a volume of water equal to the entire pool through the filter. One turnover per day keeps a residential pool clean. Heavy bather load, hot weather, or an algae recovery calls for two turnovers per day.
Does running the pump longer cost more?
On a single-speed pump, yes, run hours directly drive the bill. On a variable-speed pump, run hours matter much less because the pump draws a fraction of the power at low speed. Pump power scales with the cube of speed: half speed is roughly one eighth the power.
Single-speed or variable-speed pump?
Variable-speed wins on operating cost in almost every case, often saving $300 to $900 per year. The DOE mandate also means most replacement pumps must now be variable-speed. The only reason to keep a single-speed pump is if it is newer and still working; replace it with variable-speed when it fails.
Can I run the pump only at night?
You can, and off-peak electricity rates make it cheaper. The tradeoff is daytime is when sun drives chlorine demand and algae growth, so some daytime circulation helps. Many operators split the schedule: a long low-speed run overnight plus a short midday run for skimming.
Why does the variable-speed pump run more hours?
It moves less water per minute at low speed, so it needs more minutes to hit the same daily turnover. That is fine: the power draw is so much lower that the longer run still costs far less. Longer, slower, cheaper is the whole point of a variable-speed pump.
Sell the pump conversion in Pooly
Quote a variable-speed pump conversion with the savings math attached, send it for customer approval, and book the job in one flow.