What is a Filter Pump?

A filter pump is a motorized device used to clean the water in a pool or pond. A motor turns an impeller inside the pump, creating a vacuum that draws water into it. First, the water passes through a strainer basket that removes large debris such as leaves and twigs. Then, it goes through a filter, where smaller particles are screened out. Finally, the clean water is returned to the pond or pool via an outlet pipe.

Depending on its intended use, a filter pump may be submersible or external. Many people who keep ornamental fish ponds prefer submersible pumps, because they can be hidden out of view under the water. Experts recommend submersible pumps only for ponds of less than 1,000 gallons. For larger ponds, experts recommend external pumps, which are easier to access for cleaning and can still be hidden from view behind bushes or rocks. Swimming pools can be cleaned with either type of filter pump.

Filters for a swimming pool filter pump are generally made with diatomaceous earth (D.E.), sand, or a cartridge containing an extremely fine, accordion-folded screen. D.E. is inexpensive and widely available, and experts consider D.E. filters to be the most efficient. This is because the fossilized skeletons diatoms, the kind of algae that makes up D.E., act as tiny sponges that can trap particles as small as three to five microns.

The sand in a sand filter is specially graded for use in pool filtration and can trap particles between 20 and 100 microns in size. One of the benefits of a sand filter is that if properly maintained, it can last up to 20 years. Cartridge filters trap particles in about the same size range as sand filters, but must be replaced every two to five years. Fortunately, pool experts agree that a professional is not required to replace a cartridge filter.

Pool filters are intended to remove both physical and biological contaminants. In contrast, pond filters are meant to allow helpful bacteria to remain in the water and are therefore made of different materials than pool filters. The filtration materials used in a pond filter pump may include activated carbon, spirals of specially made plastic ribbon, and a variety of other synthetic materials.

In addition to choosing an appropriate location and filtration method for a filter pump, one may also wish to consider the pump's pressure and volume. A pump's pressure determines how quickly water will circulate through a pond or pool, while its volume determines how much water is circulated. The right combination of pressure and volume will keep a pond or pool at its cleanest.