Pool Service Glossary
DIATOMACEOUS EARTH: The filtering medium of the DE filter, this dry powder is the fossilized remains of the ancient plankton, diatom.
DIATOMACEOUS EARTH FILTER: A filter tank containing fabric covered grids which hold the DE powder 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 and is usually situated at or near the center bottom of the pool.
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 designed to entrap solids and direct 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, such as 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).
GATE VALVE: The type that spins “lefty-loosey; righty-tighty”.
GAS VALVE: An electronic valve in the pool heater that directs gas flow from the meter to the pilot and the burner tray.
GROUND-FAULT CIRCUIT-INTERRUPTER: A GFCI device protects a circuit from branching off by de-energizing the path of electricity very quickly when it senses current loss. An important safety device around water.
GUNITE: A dry mixture of cement and sand mixed with water at the “gun”; hence the name. A gunite operator “shoots” the pool’s rough shape, while finishers trowel after.
HEATER: A device used to heat the water. It may be electric, fuel operated or solar powered heat.
HEAT PUMP: The antithesis of the air conditioner, the heat pump’s cooling coil removes heat from the air while the condenser coil transfers it to water cycling through it.
INFLUENT: The water coming into and up to the impeller from the suction lines. These pipes are under vacuum pressure.
LATERALS: Elongated, capped plastic nipples at the bottom of a sand filter which are slotted to allow for water passage while keeping the sand in the filter tank.
MECHANICAL SEAL: A seal behind the impeller which prevents water from running out along the shaft of a motor. aka; pump seal.
MOTOR: A machine for converting electrical energy into mechanical energy. Your motor is known as the dry end of the filter pump. It drives the impeller, which moves the water.
MULTIPORT VALVE: A 4 or 6 position valve combining the functionality of several valves into one unit, revolutionizing pool plumbing. The six common functions are described below:
- Filter: This is normal water flow through the filter, say, 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’s a good idea to rinse for 15-20 seconds to remove any residual dirt that may “poof!” back into your pool after backwashing. Rinse flows through the water in filter fashion, say, top to bottom, but effluent is sent out the waste line.
- Recalculate: This setting bypasses the filter, water coming into the multiport does a U-turn and heads back towards the pool. Used only when the filter is broken (at least it’s circulating), or when adding specialty chemicals which specify using this setting.
- Drain / Vacuum to waste: This useful setting allows you to vacuum up large volumes of debris that would either clog the filter or pass through it because of its small size. Dirt that is vacuumed passes right out the waste line. It is also the setting of choice when draining the pool or lowering the water level (if you didn’t need to backwash, which also lowers the water level).
PLASTER: A common type of interior finish applied over the concrete shell of an in ground swimming pool.
PRESSURE GAUGE: A device indicating pressure in a filter system. Provides a determination of how the system is operating, and informs us 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 which 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: The term used to describe 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 vacuum, (or suction) while on the pressure side creates higher pressure.
RE-BAR: Reinforcement bar, used to add strength to a concrete. After excavation of an in ground pool, a steel cage is formed out of re-bar, and the gunite shell is shot over and surrounding it.
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, and forces 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 is a very useful tool in keeping the pool clean. Also called a skimmer net are the flat, “dip and flip” nets, which aren’t so useful.
STRAINER BASKET: The second line of defense is a basket at the pump. The holes in this are smaller than those in a skimmer basket, and prevent the pump impeller from clogging up.
SUCTION SIDE: The plumbing prior to and carrying water to the pump. This side is under vacuum pressure.
SPA: A filtered, hot water vessel with hydrotherapy jets and air induction. Can be portable or installed permanently. Jacuzzi is a brand name.
TEST KIT: What you should be using more frequently to determine the water balance in your pool.
TIME CLOCK: A mechanical device that controls the timed operation of your electrical equipment, primarily your filter and booster pumps.
TURNOVER: The amount of time it takes your pump to move all the water in your pool through the filter and back again. Usually, pools are designed for an eight hour turnover.
VACUUM: Refers to the low pressure condition created in the suction line. Also refers to the cleaning process of sucking leaves, algae and debris from the pool floor.
VALVES: A device placed in the plumbing line which restricts or obstructs water flow to create desired hydraulics, or may permit flow in one direction only (as in a check valve).
WEIR: The device in a skimmer that controls the amount of water coming into the skimmer, and keeps debris inside. That “flapper-gate thing”.