There are three basic types of automatic pool cleaners:
Automatic Pressure-Side Cleaners
These cleaners work off of filtered water coming from a pump. The pump is either the main circulation pump, or it can be from a dedicated booster pump. A pressure-side pool cleaner is driven by water pressure from the pump that will drive the cleaner around the pool and is also what forces the debris into a filter bag on the cleaner. The most beneficial thing about a pressure-side pool cleaner is that it doesn’t deposit the debris into your pool filter or pump basket.
Automatic Suction-Side Cleaners
These cleaners rely on suction to make them move and vacuum the debris off of the pool floor. There are several advantages to this. First, they act as a moving main drain or skimmer. When the cleaner is underwater, sucking debris into it, it is also sucking water through your filtration system.
Some suction side cleaners have the ability to scrub your pool walls. By agitating itself or its brushes as it moves around the pool, it also scrubs the walls. Since it sucks stuff right into your filter, it can remove much finer particles than a pool cleaner with a bag. Because there isn’t a need to install any additional plumbing or pumps, a suction-side pool cleaner usually costs less to install. Pools with large or large amounts of debris may not be a good candidate for this type of cleaner.
Robotic Automatic Pool Cleaners
A robotic pool cleaner uses a computer that memorizes the shape and dimensions of your pool so it can clean the entire pool automatically. Some actually come with a remote control that you can use to drive it to where you want it to go. Another advantage for one of these cleaners is that they come with a self-contained filter or filter bag. These filter(s) can be cleaned easily and some are even disposable. The fact that a lot of debris is being collected in these filters will allow for longer filter runs reducing the need for backwashing or cleaning your pool filter as much. Robotic pool cleaners are one of the best when it comes to small debris and sand or silt in the pool. Some cleaners will even climb the walls of your pool on their own eliminating the need for brushing.
Robotic cleaners are driven by electric motors inside the unit. The electricity that powers the cleaner comes through a cable that is plugged into an outdoor GFCI outlet. The current is converted from AC to low voltage DC power. Some cleaners like the Maytronics Dolphin models will operate for as little as $.15/cleaning.