Variable-speed pumps work fine on old pools.

Yes. Assuming your electrical can handle it, a variable-speed pump is one of the best upgrades you can make to an old pool system. They save a ton on electricity and run quieter.

The main thing to check is your existing pump’s voltage. If your old pump is 115V, you might need to run a new 230V circuit or buy a 115V variable-speed pump (they exist, but selection is smaller). Also, older plumbing is often smaller (1.5" pipes instead of 2"), but that’s fine—just don’t run the pump at full speed all the time. The whole point is low speed anyway.

One gotcha: some old pool controllers and timers don’t play nice with variable-speed pumps because they expect a simple on/off switch. You may need to bypass the timer and let the pump’s built-in controller handle scheduling.

Bottom line: if you’re willing to do a little electrical homework, it’s a solid upgrade. Your electric bill will thank you.