How to choose a variable-speed pool pump

A replacement pump needs to do more than fit on the pad. Start with the flow you need and an assessment of system head, then use the pump’s curve to see how it performs there. Check electrical supply, plumbing fit and controls before comparing warranty and price.

Estimate flow before comparing pumps. Our pump sizing calculator estimates flow for a chosen turnover time. Have an installer assess plumbing resistance so you can use that flow estimate to read a pump curve.

Checks Before You Buy

1. Estimate Flow and Check Equipment Limits
Divide actual pool gallons by the chosen turnover time in minutes to estimate GPM. Use that as a starting point, then assess the flow limits of your filter, heater, cleaner and salt cell. Have an installer check any applicable minimum-flow requirement.
2. Have Plumbing Resistance Assessed
Ask an installer to assess total dynamic head at the intended flow. Include pipe diameter and length, fittings, the filter’s condition, heaters and water features in that assessment, then compare pumps at that resistance.
3. Read flow from the performance curve
Use the manufacturer's performance curve to read delivered flow at your head. Compare that point on the curve with the flow you need, rather than buying by the maximum-flow number.
Ask for the model's curve before ordering. Use it to compare the proposed operating point with your required flow.
4. Check the electrical supply and the plumbing fit
Have the electrical supply checked against the pump manual. Compare union spacing, port size and body dimensions with your pad. Include any wiring or plumbing changes in the installed quote.
5. Check scheduling and automation
Find out which scheduling controls the pump supports and whether they work with your pool automation. Then compare measured watts and runtime at a flow that meets your equipment’s needs.
Follow the pump manual’s power-supply instructions. An external timer can interrupt an onboard schedule. Check the supported control arrangement before adding one.
6. Check Model Support and Warranty Terms
Look up the exact model on the manufacturer's page to check its status and support. For a discontinued model, find out what parts and warranty coverage remain before comparing installed costs.
Read the model's warranty for your seller and installer. Compare parts, labor, installation conditions and registration requirements alongside the price.

Use the checklist to compare installed quotes

Ask each installer to name the model and show its proposed flow at your assessed head on the pump curve. Include electrical and plumbing work, controls and warranty coverage so you’re comparing complete installations.

Take the turnover-flow estimate from the sizing calculator and have an installer assess system head. Compare the model curves at that head, then assess flow and electrical input at the proposed operating speeds.

Pump Sizing Calculator →Pump Runtime & Cost Calculator →Compare pump electricity costs and payback →

Frequently asked questions

Will more horsepower give me the flow I need?

More horsepower on the label doesn’t show you the flow through your plumbing. Read the pump’s performance curve at your system head and choose one that meets the required flow within equipment limits. Then compare watts at that operating point.

Can I use an external timer with this pump?

Use the scheduling controls or compatible automation in your exact pump manual. A timer that cuts power can interrupt an onboard schedule. Compare measured watts, flow and runtime when judging any energy saving.

Does horsepower tell me the delivered flow?

Horsepower describes power rather than the flow your plumbing will receive. Read the manufacturer’s performance curve at your total dynamic head to see whether the model can meet the required flow.

Which pump efficiency rules apply where I live?

Before buying, have your installer check the efficiency requirements for your equipment class and location. Use the current guidance, including the California Energy Commission resource linked in the methodology, rather than choosing by nameplate horsepower.

What warranty terms should I check before buying online?

Read the exact model’s current warranty terms for the proposed seller and installer. Confirm seller authorization, the covered parts and labor, installation requirements and any registration deadline. Compare that coverage with the installed quote before purchasing.

How do I estimate my daily pump runtime?

Enter your pool’s gallons, measured flow and chosen turnover count to estimate runtime. Make sure the schedule also meets filtration, skimming, heater, cleaner and salt-cell needs. Keep testing FC and pH to check sanitation as you adjust the schedule.