A suction-based pool cleaner is a self-propelled vacuum that travels around your pool by using the suction created from your pump. A hose connects from the head of the cleaner to the opening in your pool skimmer.
Most suction-based cleaners have one moving part: the diaphragm. The diaphragm looks like a rubber sleeve with a mouth at one end. The suction from the pump causes the mouth to open and close, creating a vacuum effect that draws the cleaner forward.
Most suction-based cleaners simply follow the water current in the pool. As a result, they can get caught on ladders and/or miss sections of the pool. If you are having problems with your suction-based cleaner, start by looking at the direction in which your return ‘jets’ are facing. They should generally point slightly down and toward the center of the pool, to encourage the cleaner to cover more surface area.
A suction-based cleaner is often referred to as a ‘Kreepy Krauly,’ though they are rarely Kreepy brand anymore. Colloquially, people will know what you are talking about, but it is highly recommended that you know the actual brand of your suction-based cleaner, as replacement parts are brand-specific.