Browse our complete library of commonly used terminology relevant to swimming pool cleaning equipment and processes.
Air bleeder assembly: Located on the top of the filter, sometimes accompanied by a pressure gauge, the air bleeder is opened to release air trapped in the filter.
Automatic pool cleaner: A device that agitates or vacuum debris from the walls and floor of the pool.
BTU (British Thermal Unit): A unit of measurement for the use of gas by a gas appliance. Pool heaters are rated by their consumption.
Backwash: The process of thoroughly cleaning the filter medium and elements by reversing the flow of water through the filter to waste.
Ball Valve: A device with a hollowed -out ball inside that can be turned with an external handle to decrease or increase flow.
Blower: Plumbed into a spa return line, air is injected to produce refreshing bubbles and a hydrotherapy effect in the spa.
Booster pump: Secondary to the filter pump, a booster pump is used to power an automatic pool cleaner, such as a Polaris or Letro brand.
Capacity: Refers to gallonage of the pool (see chart).
| Round Pool Formula | Oval Pool Formula |
Rectangular Pool Formula |
Diameter x Diameter x Average Depth of water(Ft.) x 5.9 = Total Gallons(US) |
Length of pool x Width of pool x Average Depth of water(Ft.) x 5.9 = Total Gallons(US) |
Length of pool x width of pool x Average depth of water(Ft.)x 7.9 = Total gallons(US) |
For liters: Take gallons (US) x 3.78543 = Liters |
For liters: Take gallons (US) x 3.78543 = Liters |
For liters: Take Gallons (US) x 3.78543 = Liters |
Example: 24' Round Pool 48" deep 42" Water depth |
Example: 12'x24' Oval Pool 48" deep 42" Water depth |
Example: 12'x24' Rectangular Pool 48" deep 42" Water depth |
Cartridge: As a filtration type, a cartridge is a pleated, porous element through which water is passed.
Check valve: A one-way flow device.
Chlorinator: A device that enables safely controlled introduction of chlorine into swimming pool water.
Chlorine generator: Functioning like a miniature chlorine factory, this device creates its own sanitizer for a swimming pool.
Circulation system: The "circuit" of plumbing that continuously carries water out of the swimming pool, through the pump and filter, and back into the pool.
Conduit: A pipe—usually gray PVC or flexible PV—that carries wires from a source (e.g., a time clock) to a load (e.g., a pump motor).
Coping: As the capstone on top of the bond beam that finishes the edge around a pool or spa, coping medium may precast concrete or brick. On vinyl liner pools, pre-fab coping normally is part of an integrated system for the wall, vinyl liner, and deck.
Coupling: A plumbing fitting that joins two pieces of pipe.
Diatomaceous Earth (DE) filter: A filter tank with fabric-covered grids that hold DE—a dry powder comprised of the fossilized remains of the ancient plankton diatom—up against the flow of the water.
Diverter valve: Used in a twin port skimmer, a diverter allows the operator to manipulate the amount of flow from the main drain and skimmer to the pump.
Drain: Also called the main drain, this plumbing fitting is the start of one suction line to the pump, usually situated at or near the center bottom of the pool.
Effluent: The water that flows out of the pump, on its way through the filter, heating and treating equipment, and returning to the pool. (Also known as the pressure side).
Elbow: A 90-degree or 45-degree plumbing fitting used where pipes take a turn.
Filter: A device used to remove particles suspended in the water by pumping water through a porous substance or material.
Filter element: A device inside a filter tank that entraps solids and directs water through a manifold system to exit the filter. (Cartridge filter elements and DE filter grids are two examples.)
Filter medium: A finely graded material—e.g., sand, diatomaceous earth, polyester fabric or anthracite coal—that removes suspended particles from water passing through it.
Filter pump: The device that pulls water from the pool and pushes it through the filter on its way back to the pool.
Filtration rate: The rate of water pumped through a filter, in gallons per minute (gpm).
Heater: An electric, fuel-operated, or solar- powered device that heats swimming pool water.
Heat exchanger: A set of eight or 10 ribbed copper tubes that absorb the heat produced below it, transferring it to the water cycling through the exchanger tubes.
Heat pump: The antithesis of the air conditioner, a heat pump's cooling coil removes heat from the air while the condenser coil transfers it to the water cycling through it.
Hydrostatic pressure: A force involving built-up ground water that creates upward pressure beneath the pool shell.
Hydrostatic relief valve: Fitting(s) installed in the floor of the pool to manually or automatically release hydrostatic pressure beneath the pool by allowing ground water into the pool.
Impeller: The rotating vanes of a centrifugal pump, an impeller's action creates the flow of water. The impeller is shaft-driven by an electric motor.
Influent: The water coming into and up to the impeller from the suction lines. The pipes involved are under vacuum pressure.
Jandy Valve: A brand name of a three-way valve, said to have simplified pool plumbing.
Jet pump: Used in spas to provide additional thrust into the hydrotherapy jets.
Laterals: Elongated, capped plastic nipples at the bottom of a sand filter that are slotted to allow water passage while keeping the sand in the filter tank.
Load: An electric device that consumes energy—i.e., placing a load on the source.
Low water suction: An influent fitting, typically low on the wall in the deep end of a vinyl liner pool—a lower-cost alternative to a main drain.
Mechanical seal: A seal behind the impeller that prevents water from running out along the shaft of a motor (also called a pump seal).
Motor: A machine for converting electrical energy into mechanical energy. A motor is known as the dry end of the filter pump. It drives the impeller, which moves the water.
Multiport valve: A four-position or six-position valve that combines the functionality of several valves into one unit, revolutionizing pool plumbing. (See table for the common functions).
Function |
Action |
Filter |
This is normal water flow through the filter—for example, top to bottom. This is where the valve sits 99% of the time. |
Backwash |
When the pressure gauge indicates, you will need to backwash the filter. When the handle is turned to backwash, the flow through the filter is reversed, say, bottom to top. The effluent water (out of the filter) is directed to the waste line. |
Rinse |
After backwashing, it is best to rinse for 15-20 seconds to remove any residual dirt that may "poof" back into a pool after backwashing. Rinse flows through the water in filter fashion—i.e., top to bottom—but effluent is sent out the waste line. |
Recirculate |
This setting bypasses the filter, as water coming into the multiport does a U-turn and heads back towards the pool. Used only when the filter is broken or when adding specialty chemicals that specify using this setting. |
Drain / Vacuum to waste |
Setting allows vacuuming up large amounts of debris that would normally clog the filter or pass through it due to the filter's small size. The debris then passes right out the waste line. This setting also is used when draining the pool or lowering the water level. |
Plaster: A common type of interior finish applied over the concrete shell of an in-ground swimming pool.
Pressure check: A test for the rate of water flow; or a test for leaks in plumbing by placing a line in question under pressure and waiting for the pressure to drop.
Pressure gauge: A device that indicates pressure in a filter system and provides a determination of how the system is operating. Also informs when service is required.
Pressure side: The return side of the plumbing; the section from the pump impeller towards the pool.
Pressure switch: A switch used in pool heaters that opens when the flow rate is insufficient for safe heater operation. This disrupts the circuit in the heater, preventing it from firing.
Plunger: The sliding disc assembly that changes valve position in a push-pull valve. For example: up for backwash, down for filtration.
Push-pull valve: A two-position valve used for backwashing sand or DE filters.
Pump: A mechanical wet-end, powered by an electric motor, which causes hydraulic flow and pressure for the circulation of the pool water.
PVC: Polyvinyl chloride, which is used to make flexible and rigid PVC pipe used for pool plumbing.
Rate of flow: Quantity of water flowing past a designated point within a specified time period, measured in gallons per minute (gpm).
Restricted flow: A condition preventing full flow of water. Restriction can occur with full skimmer or strainer baskets, obstructions in the plumbing, dirty filter, undersized plumbing or equipment , or placing devices like heaters, cleaners, or fountains in the circulation system. Restriction on the suction side creates higher
Sand filter: A filter tank—usually fiberglass or ABS plastic—filled with sand and gravel. The pump diffuses water over the top of the sand bed, forcing it through the sand and into the laterals on the bottom.
Skimmer: A surface skimmer is a plumbing fitting set at water level, containing a weir mechanism and a debris basket. The skimmer is part of the suction-side circulation system.
Skimmer basket: Beneath the lid, the basket strains debris as the first line of defense in filtering the water.
Skimmer net: Attached to a telescopic pole, a leaf rake that is a very useful tool in keeping the pool clean.
Strainer basket: The second line of defense in filtering pool water is this basket at the pump. The holes in the strainer basket are smaller than those in a skimmer basket, thereby preventing the pump impeller from clogging.
Suction side: The plumbing prior to and carrying water to the pump. This side is under vacuum pressure.
Tee: A plumbing fitting used to bring two pipes together into one, or vice-versa.
Time clock: A mechanical device that controls the timed operation of electrical equipment—primarily a filter and booster pumps.
Turnover: The amount of time it takes the pump to move all the water in the pool through the filter and back again. Usually, pools are designed for an eight-hour turnover.
Underdrain: The lower collection system in a filter that directs filtered water back toward the pool. It also distributes water in reverse during backwashing. (Also see Laterals).
Vacuum: Refers to the low-pressure condition created in the suction line, as well as the cleaning process of sucking leaves, algae, and other debris from the pool floor.
Valves: A device placed in the plumbing line that restricts or obstructs water flow to create desired hydraulics, or may permit flow in one direction only (as in a check valve).
Venturi: Increasing water velocity by restricting pipe size.
Vinyl liner: One type of interior finish. The liner is draped over a sand or cementitious floor, and locked into the top of the wall.
Weir: The device in a skimmer that controls the amount of water coming into the skimmer, keeping debris inside.
Glossary Sources:
http://www.servicemagic.com/article.show.Swimming-Pool-Glossary.13239.html
http://outdoorlivingpools.com/swimmingpooltermsanddefinitions.shtml