Are Variable-Speed Pool Pumps Worth It?

The pump is usually the biggest electricity user in a backyard pool system, because it runs for hours every day from May to October. That’s why the pump is where efficiency upgrades pay off most. This page answers the questions we hear most often about variable-speed pumps, including the less flattering ones.

What’s actually different about a variable-speed pump?

An older single-speed pump has one setting: full speed, all the time it runs. A two-speed pump adds a low setting. A variable-speed pump uses a permanent-magnet motor and a controller that lets you set almost any speed and schedule several speed changes through the day.

Why does running slower save so much?

Physics, mostly. For the centrifugal pumps used on pools, the power a pump draws falls much faster than its flow. Under the “affinity laws,” halving the speed cuts flow roughly in half but cuts power draw to roughly an eighth. So a pump running at half speed for twice as long moves the same amount of water for a fraction of the energy.

Real-world savings are smaller than that ideal because of plumbing resistance, filter condition and motor efficiency, but they are still large. Manufacturers such as Hayward and Pentair publish energy estimates for their models, and they are worth comparing for your pool size.

What are the downsides?

• Higher purchase price. A variable-speed pump costs more than a single-speed one. The savings repay that over several seasons, not one.
• It has to be programmed. A variable-speed pump left running at high speed all day throws away most of the benefit, and it happens more often than you’d think.
• Some equipment needs a minimum flow. Heaters, salt cells, in-floor cleaners and some suction cleaners only work above a certain flow. The schedule has to account for that.
• Electronics don’t like water or power surges. Good installation, proper bonding and a dry location matter more than with an old pump.

How should I set one up?

A typical schedule uses three or four blocks:

1. A short higher-speed period to prime, skim the surface well and run the cleaner or heater.
2. A long low-speed period for most of the day’s filtration.
3. A medium boost after heavy use or when adding chemicals.

If you’re on time-of-use or ultra-low overnight electricity rates in Ontario, shifting the longest low-speed block to cheaper hours stretches the savings further. Check which rate plan your account is on with your local utility before you plan around it.

Aim to turn the full volume of the pool over at least once a day in swimming season, more in hot weather or heavy use. Your installer can work out the flow at each speed for your plumbing.

Is my old pump worth replacing now, or should I wait until it fails?

This is a genuine judgment call, and it depends on the age of the pump, how many hours you run it, and what you pay for power. A pump that is near the end of its life anyway is an easy decision. A five-year-old single-speed pump in good condition is closer: the savings are real, but so is the cost of replacing something that still works. We would rather show you the numbers than push a replacement.

Questions we get asked

Will a variable-speed pump work with my existing filter and heater?

Usually, yes, as long as it is sized and programmed for the flow your heater and filter need. Very old or undersized plumbing can limit the benefit.

Is a variable-speed pump quieter?

At low speed, noticeably. Many owners mention that first, before the hydro bill.

Do I need an electrician?

Pump replacements involve wiring and bonding, so they should be done by qualified people. Our equipment service and installation team handles pump swaps and programming.

For how the pump fits with the filter and the rest of the system, see pool pumps and filters explained.