poolnerd

Acid– Usually, in the context of pools, refers to muriatic acid, a diluted hydrochloric acid.

Alternates– Additional vertical bars of reinforcing steel in the cove of a pool wall located between the normal 12-inch spacing of vertical bars. This additional reinforcing strengthens the pool wall against added loads outside the pool wall (such as from surcharges or expansive soil). Alternates are good, more and bigger are generally better, but follow the advice of the pool’s engineer.

Backwash– One method of cleaning sand or diatomaceous earth (DE) filters. Involves reversal of water flow through the filter, with the collected dirt and debris being sent to the waste port.

Bond beam– A structural element of a gunite or shotcrete pool. A bond beam is usually the topmost part of the pool wall, and is about 12 inches wide. It is usually capped with coping (such as stone, brick or concrete), and faced on the pool side with tile.

Circuit breaker– An electrical device that shuts off electricity when a circuit draws too much current. Sometimes known as simply a “breaker,” they can be located in the main service panel or a subpanel.

Concrete– A mixture of portland cement, aggregate (rock), sand and water.

Conditioner– Cyanuric acid. Added to pool water to help protect chlorine from sunlight, which can break down chlorine. Think of conditioner as sunscreen for chlorine.

Cove– The curving transition from the vertical wall to the horizontal floor, at the bottom of a pool wall.

Coping– The finish material applied over the top, horizontal edge of a pool. Can be of cast concrete, cantilever concrete, brick, stone and other materials.

DE– see diatomaceous earth.

Diatomaceous earth– the skeletal remains of marine diatoms. Used as a filtering agent in some pool filters.

Engineer– The professional civil or structural engineer responsible for the structural design of the pool.

Filter– the piece of equipment used for filtering dust and other fine debris from the pool water. Filtering agents include DE, silica sand, or a cloth cartridge.

GFI– See GFCI.

GFCI– Ground Fault Circuit Interrupter. Usually seen as an electrical outlet with two small buttons between the plugs (”test” and “reset”). Monitors the flow of electricity in the circuit, and trips (shuts off) if any of the electricity goes to ground. Basically, a safety device to protect against shock and/or electrocution.

Gunite– A trade term for dry-mix shotcrete. Gunite is a special type of sprayed-on concrete, comprised of mixture of sand and portland cement, which is moved through a hose by compressed air. A small amount of water, just enough to induce hydration, is added at the nozzle. It’s structural strength is usually around that of concrete used in sidewalks and patios, about 2000 psi.

Hair and lint pot– the strainer basket on the front of a pool pump.

Impeller– The part of a pump connected to the motor shaft that, in a pool pump, uses centrifugal force to move water. Water enters the center of the impeller and is spun to the outside and channeled to the pump outlet.

Main drain– The drains in a pool or spa. Not used for draining the pool, they are actually an intake point for water supply to a pump.

Mortar– A mixture of portland cement, sand and water, sometimes with hydrated lime (or lime putty) added for “plasticity” or workability. Used to “glue” brick or block together, or to set brick or stone to the pool structure.

Pebble finish– An exposed-aggregate pool finish, used instead of plaster. It’s composition is similar to regular pool plaster, with the chief difference being the addition of small tumbled pebbles used as part of the aggregate (see plaster). After it is troweled to a certain hardness, misting sprayers are used to remove the top part of the plaster, exposing the pebbles in the aggregate plaster mix.

Pebble Tec– A particular brand of an exposed-aggregate pool finish.

Portland cement– Gray cement “powder” used in concrete and mortar.

Plaster– Pool plaster is a mixture of white portland cement, a white aggregate (usually crushed marble or white sand), and water. Often, an additive such as a pozzolan (Meta Max, for example) is added to improve particular characteristics of the plaster. Plaster is the surface inside the pool, below waterline. It must be smooth and waterproof.

PSI– Pounds per Square Inch, a measure of pressure.

Raised bond beam– An elevated portion of a pool wall, usually used to “hold back” soil. The bond beam itself is usually located lower down, with a raised portion of the pool wall above. Often faced with brick, stone or tile.

Rebar– Reinforcing steel rods embedded in concrete for additional strength in tension (to resist pulling — or bending — forces).

Retaining wall– A reinforced concrete or masonry wall that is engineered for the purpose of retaining (or holding back) soil.

Return line– Sometimes known simply as a return, it refers to a pipe or pipe inlet into the pool that brings filtered water back to the pool. A return line is under pressure when the pump is running; this means that a leak in this line would drip or spray water.

Service panel– The main electrical panel, often where your electric meter is located. The service panel contains the service disconnect (”main”) circuit breaker, which shuts off all electrical power.

Shotcrete– A special type of sprayed-on concrete, brought to the jobsite by a ready-mix concrete truck, and pumped to the pool site by a concrete pump and compressed air.

Sign-off card– Card for building inspector to sign, indicating official approval of a portion of the work.

Skimmer– An water inlet for the pump that contains a strainer basket. A skimmer removes floating debris from the pool’s surface as water is drawn in for the pump.

Standard Plan– A structural engineering plan that covers common details of most pool construction, which has already been approved by the engineer or plan checker at the building department. A standard plan is usually much cheaper than a custom or site-specific structural plan.

Suction line– A pipe that brings water from the pool or spa to the pump. Suction lines are under vacuum when the pump is running; this means that a leak in a suction line won’t drip water, it will suck in air. A suction line can be referred to by the system it operates on. For example, “spa suction” means a suction line associated with the spa.

Subpanel– a electrical panel that contains circuit breakers, and is separate from the main or service panel.

Surcharge– An added load on a structural element like a pool wall, a foundation, or a retaining wall. Since an extra load has been added, the structural element must be strengthened to compensate.

SWG– An acronym for “Salt Water Generator,” often seen on swimming pool forums. This is not entirely accurate, however — “Salt Water Chlorine Generator” would be better, or simply “salt cell.” Anyway, this is a device that uses salt water to make chlorine, specifically, hypochlorous acid (HOCl), the killing form of chlorine that is desirable in pools.

Timeclock– A mechanical timer for a pool pump.

Water feature– A decorative element using flowing water such as fountain or waterfall.

Weir– a surface over which water flows; in the context of pools, it is usually
used to refer to a part of a skimmer, over which water flows, trapping debris behind it when the pump shuts off.

NOTE: If there are other terms that you aren’t sure about that can be added to this list, please email me — nerd(at)poolnerd(dot)com — so that I can make this list more complete.