How Does an Automatic Pool Cleaner Work? | 3 Types, Explained

Automatic pool cleaners remove debris using one of three mechanisms: suction, pressure, or a self-contained robot.

Most pools that stay clean without weekly brushing owe it to one of these machines, and the type you need depends entirely on your pool’s setup. Understanding how an automatic pool cleaner works is the first step to picking the right one, because the three main categories are mechanically different and use completely different parts of your pool system. Here’s a direct breakdown of how each style gets the job done.

The Three Main Types of Automatic Pool Cleaners

There are three families of automatic pool cleaners: suction-side, pressure-side, and robotic. The fundamental difference lies in their power source and whether they rely on your pool’s plumbing.

The most important distinction is this: suction and pressure cleaners depend on your pool’s existing pump and filter system, while robotic cleaners are entirely self-contained units.

• Suction-side cleaners attach to your skimmer or a dedicated suction line. They use the pool pump’s suction to pull water and debris through the cleaner, up the hose, and into your pool’s filtration system.
• Pressure-side cleaners connect to your pool’s return line. They use the force of water returning from the pump to move around and collect debris into their own attached bag, which you empty manually.
• Robotic cleaners are independent. They plug into a standard electrical outlet and use their own onboard motor, brushes, and internal filter to clean the pool without using the pool’s filtration system at all.

How Suction-Side and Pressure-Side Cleaners Operate

Suction-side and pressure-side cleaners are mechanical devices that rely on your pool’s main pump to function, so they only work when the pump is running.

Suction-side models are often the most affordable and are a good fit if you have a capable pool pump. They move randomly across the pool floor, and you may notice them “hop” or change direction—this happens when an internal valve shifts the vacuum suction. The tradeoff is that they route all the debris straight into your pool filter, which means you’ll need to clean the filter more often.

Pressure-side cleaners, which may require an additional booster pump to operate effectively, use the return water’s pressure to roam the pool. They collect leaves and larger debris into a dedicated bag, which keeps load off your main filter but adds installation complexity and energy use. This kind of cleaner is often a good choice for pools that collect a lot of large debris like leaves or twigs, since the debris goes into a bag you simply empty rather than into the pool’s filter.

How Robotic Pool Cleaners Work on Their Own

Robotic cleaners are the most independent type. They are self-contained machines that you lower into the pool, plug into a standard wall outlet, and let run until they finish their cycle.

To start a robotic cleaner, you place it in the pool and press the Start/Stop button on its dedicated control box. The control box, not your pool’s plumbing, runs the unit. Because it has its own motor and filtering system, a robotic cleaner runs independently of your pool’s pump and filters, meaning it doesn’t add load to your filtration system or require special plumbing. This also means robots are the easiest choice for pools without compatible suction or return lines.

Robotic cleaners are programmable and typically work by mapping the pool floor in an efficient path, with many models also climbing walls and some even addressing the waterline. Depending on the model, they will run for a set time and then automatically shut off.

Because they plug into an electrical outlet, the main caveat with robotic cleaners is outlet placement and electrical safety near the water. They also represent a higher upfront investment, but they deliver the most thorough, hands-off cleaning.

Which Pool Cleaner Type Is Right for You?

Choosing between the types comes down to your pool’s plumbing, your budget, and how much debris you deal with. Here’s a quick comparison to guide your decision.

If you are still deciding between models and want to compare top-rated options, our roundup of the best automatic pool cleaners on the market breaks down the leading contenders for every pool type.

A common mistake is assuming every model climbs walls or cleans the waterline. Wall-climbing and Wi-Fi features vary widely by model, so check the specs. Also remember that a robotic cleaner costs more upfront, while a suction-side unit is cheaper upfront but increases the workload on your existing filter and pump. The right pick simply matches the machine’s power source to what your pool already has—or upgrades you to a self-contained robot if you’d rather not think about it at all.