Pool Equipment and Maintenance Glossary of Terms


A pool maintenance system that will vacuum or displace debris from the pool interior automatically.


The process of thoroughly cleaning the filter by reversing the flow of water through the filter media and sending the dirt and rinse water to waste.


A mechanical or electrical device for dispensing bromine at a controlled rate. Most often a canister or floater filled with tablets of bromine.


Abbreviation for British Thermal Unit. The amount of heat necessary to raise 1 lb. of water by 1 degree Fahrenheit.


An arrangement of pipes, gates and valves by which the flow of water may be passed around a piece of equipment or diverted to another piece of equipment; a controlled diversion.


A pool or spa water filter that uses a replaceable porous element made of paper or polyester.


A device located inside the heater providing for the transfer of heat from the heat source to the water.


A fossil-fueled, electric or solar device used to heat the water of a pool, spa or hot tub.


The work done per unit of time. 1 horsepower equals 33,000 foot-pounds of work per minute or approximately 746 watts. Motors for pumps are rated in horsepower.


The rotating member of a pump. The part of the pump that moves the water.


A fitting in the pool or spa on the water return line from the equipment that water returns to the pool. Usually the last thing on the return line.


A water-sanitation device that uses electricity to generate metal ions, which are dispersed in the water. It works by passing a low-voltage DC current through a set of metallic (usually copper and silver) electrodes placed in line with the circulation equipment. The copper is an algaecide, while the silver is a bactericide. Does not remove swimmer waste.


This term usually refers to a plumbing fitting installed on the suction side of the pump in pools, spas and hot tubs. Sometimes called the drain and is located in the deepest part of the pool, spa or hot tub. It is not a drain, such as a drain on a kitchen sink. Main drains do not allow the water to drain to waste but rather connect to the pump for circulation and filtration.


The branch pipe arrangement that connects several input pipes into one chamber or one chamber into several output pipes. A filter manifold connects several input pipes from the filter septa back into one common pipe.


Also called a rotary-type backwash valve – This valve replaces as many as 6 regular gate valves. Water from the pump can be diverted for various functions by merely turning the valve handle. The water may be sent to waste, used for backwashing, bypassing the filter for maximum circulation, for normal filtration, filtering to waste (rinse), or the valve may be closed to not pass water. The pump must be off before changing a valve setting.


A cover that, when placed on the water’s surface of a pool, spa or hot tub, increases the water temperature by absorption and transmission of solar radiation; reduces evaporation and prevents wind-borne debris from entering the water.


Typically, this consists of panels or coils of plastic or metal through which water passes to increase the temperature from the sun’s radiant heat.


This term can be used to define any number of devices that use suction to collect dirt from the bottom and sides of a pool or spa. Most common is a vacuum head with wheels that attaches to a telepole and is connected to the suction line usually via the opening in the skimmer. It must be moved about by a person, and debris is collected in the filter.


A fitting or device that consists of a tube constricted in the middle and flared on both ends. A fluid’s velocity will increase and a fluid’s pressure will decrease while passing through the constriction. Placing a tube or pipe at the constriction point creates a vacuum. Fluid or air can then be drawn in through the tube. A hydro-therapy jet draws air in and mixes it with the water using this principle.


The vinyl membrane that acts as the container to hold or contain the water.


Also called skimmer weir – Part of a skimmer that adjust automatically to small changes in water level to assure a continuous flow of water to the skimmer. The small floating “door” on the side of the skimmer that faces the water over which water flows on its way to the skimmer. The weir also prevents debris from floating back into the pool after the pump shuts off.