How to Match a Pool Cleaner to Your Pump's Flow Rate

Check your pump's flow before you buy

Your pool pump does two jobs: it recirculates water through the filter and it supplies the flow that many pool cleaners depend on. The two jobs do not need the same flow. The ENERGY STAR program notes that filtration only requires about half the flow rate of running a pool cleaner. If you size a cleaner to the pump's maximum rating, you may be disappointed when the pump is set to a lower speed for daily filtration.

Start by finding the flow your pump delivers at the speed you plan to run it. The flow is stated in gallons per minute (GPM) or gallons per hour (GPH) on the pump's nameplate or in the maker's spec sheet. A single-speed pump runs at one fixed speed, so the rated flow is the number to compare. A variable-speed pump can be programmed to run at different speeds, so check the flow curve for the speed you intend to use for cleaning rather than the maximum the pump can produce. For more detail on how flow is stated, see flow rate and how to read pool cleaner specs.

Cleaners that run off the pump

Two common types of pool cleaner use the pump's flow directly. A suction-side cleaner connects to the skimmer or a dedicated suction line and rides on the pump's pull. A pressure-side cleaner connects to a return line and rides on the pressure of the water coming back to the pool; many designs need a dedicated booster pump to supply enough flow.

Both types publish a flow range in their specifications, expressed as a minimum and a maximum in GPM. Below the minimum, the cleaner will not move fast enough to cover the floor or climb walls. Above the maximum, the excess flow can strain the cleaner and the plumbing. Compare that range against the number you found in the first step, and account for the resistance of the hose run, since hose selection changes how much flow actually reaches the cleaner.

For a deeper look at what makes a pump-powered cleaner work well, read about suction power and the pump horsepower requirement.

• Minimum flow: below this, the cleaner stalls, drifts, or fails to climb.
• Maximum flow: above this, the cleaner can cavitate or the system can be overstressed.
• Booster requirement: some pressure-side models list flow only for the booster pump, not the main pump.

When flow is too low

If your pump cannot deliver the cleaner's minimum flow, the cleaner will crawl along the floor, skip patches, and make little progress on walls. Before you buy a bigger pump, check the easy causes: a dirty filter bag or cartridge, a partially closed valve, or a hose that is too long or too narrow for the cleaner. Each one reduces the flow that actually reaches the cleaner.

A variable-speed pump can often solve the problem without new equipment. You can program a higher speed for the cleaning cycle and a lower speed for filtration. ENERGY STAR notes that conventional single-speed pumps are set to run at the higher speeds required by a pool cleaner and waste energy during filtration because they run faster than necessary. If your pump cannot be programmed, see the pool cleaner installation guide for setup changes, or consider a cleaner that does not depend on the pump.

When flow is too high

Excess flow is the other side of the problem. A cleaner with a narrow maximum rating on a pump that pushes a lot of water can put needless strain on the filter, the plumbing, and the cleaner itself. ENERGY STAR's guidance is that slower circulation rates put less strain on the filters, plumbing, and other parts of the system, reducing the chance of leaks, repairs, or premature component replacement.

If your pump's flow at the cleaning speed is above the cleaner's maximum, you have a few options. Fit a flow regulator in the cleaner's hose, choose a cleaner with a wider flow band, or switch to a robotic cleaner that runs on its own pump. Robotic cleaners and cordless models draw power from a low-voltage supply, not the filter pump, so they are immune to this problem.

Robotic cleaners skip the pump entirely

A robotic pool cleaner is a self-contained unit with its own motor and filter. You drop it into the water, plug in its power supply, and it moves on its own. The ENERGY STAR program describes robotic cleaners as powered by low-voltage electricity, rather than your pool pump or a booster pump, and they collect dirt and debris in built-in filters.

Because a robotic cleaner does not use the pump's flow, you do not need to compare GPM ratings. This makes robotic cleaners the easiest choice when your pump is old, undersized, or programmed for low-speed filtration. See the best robotic pool cleaners for in-ground pools and cordless robotic pool cleaners for models that work in any pool system.

What to pick for your pump's flow

Questions

How do I find my pump's GPM?

Look at the pump's nameplate or spec sheet. Single-speed pumps list a single GPM rating, while variable-speed pumps provide a flow curve for each speed. If you cannot find the number, measure the time it takes to fill a known volume from the return line, but that method is rarely precise. The maker's documentation is the most reliable source.

What happens if the flow is too high for the cleaner?

Excess flow can force the cleaner to move too fast, miss patches, or even cause cavitation in the pump. It also adds strain to the filter and plumbing. ENERGY STAR notes that slower circulation rates put less strain on the system, so you want a cleaner that matches a moderate flow rather than a maximum.

Can I lower my pump speed to match a cleaner?

Only if you have a variable-speed or multi-speed pump. You can program a slower cleaning speed that still meets the cleaner's minimum GPM. This also saves energy because filtration needs only half the flow rate of a pool cleaner, as ENERGY STAR points out.

Do robotic cleaners need a booster pump?

No. Robotic cleaners run on low-voltage electricity and use their own motor and filter. They do not connect to the pump or booster pump, so they work in any pool regardless of the flow rate.

What is a flow regulator and when do I need one?

A flow regulator is a valve that fits into the cleaner's hose to limit the water that reaches the cleaner. It is useful when the pump's flow is comfortably above the cleaner's minimum but below its maximum. It prevents the cleaner from moving too aggressively and reduces strain on the plumbing.