Most pool pumps are classified as self-priming centrifugal pumps. This allows them to be placed above the waterline.
If the pump is not self-priming, it must be placed below the waterline so that the pump is primed by gravity.
Some pool pumps reduce power consumption by having two different speeds, while many modern European motors have been designed to run at one speed, 24 hours a day using less energy. Many prefer the slower pump because it allows for decreased resistance in the pipes, thus reducing the amount of energy necessary to move water.
Modern pool pumps also use a hair and leaf strainer in the form of a small filter basket. This helps keep hair, leaves or other debris from compromising the pump’s impeller.