JANDY VALVE: brand name of a three-way valve, which has simplified pool plumbing

JET PUMP: used in spas to provide additional thrust into the hydrotherapy jets

LADDER: structure used for getting in and out of the pool; a double-access ladder straddles the pool wall of an aboveground pool; an in-pool ladder is located in the pool only

LADDER BUMPERS: rubber caps or inserts that protect the pool plaster or vinyl liner from the sharp steel ends of the ladder

LATERALS: (1) elongated, capped plastic nibs at the bottom of a sand filter, which are slotted to allow for water passage while keeping the sand in the filter tank (2) see also underdrain

LEACHING: process of extracting a mineral from plaster pool interiors or tannic acid from wooden hot tubs

LEAF BAGGER: device that attaches to a telepole and a garden hose; pressure from the garden hose creates a suction by which leaves and large debris are sucked into a large mesh bag

LEISURE SURFACING: see NataDek

LIFELINE: rope line across a pool to designate a change in slope in the pool bottom, or the beginning of deep water; usually supported by regularly spaced floats

LIGHT NICHE: area in a pool or spa that house the underwater light

LINER: see Natatec Membrane Systems

LOAD: electric device, which consumes energy, placing a load on the source

LOWER COLLECTION SYSTEM: see underdrain

LOW WATER SUCTION: (1) influent fitting, typically low on the wall in the deep end of a vinyl liner pool (2) a cheaper alternative to a main drain

LUMINA SYSTEM: See Uniwall Systems

MAIN DRAIN: see drain

MANIFOLD: 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 sept back into one common pipe

MARCITE: originally a brand name for a white plaster finish coat from 1/8-1/2-inch inch thick applied over the gunite or shotcrete

MECHANICAL SEAL: (1) seal behind the impeller that prevents water from running out along the shaft of a motor (2) also called a pump seal

MECHANICAL SYSTEMS: integrated equipment including filters, piping, valves, pumps, disinfecting units and automatic control systems

MEMBRANES: see Natatec membrane systems

MICRON: (1) unit of length equal to 1 millionth of a meter (2) used to describe the pore size of filter media; (sand filters have openings of 25 to 30 microns; cartridge filters have openings of 8 to 10 microns; and D.E. (diatomaceous earth) filters have openings of 1 to 5 microns); a granule of table salt is between 90 to 110 microns

MODULAR SYSTEM: cellular hi-rate sand filtration system utilizing an expandable modular cell design for increased flow rates

MOTOR: (1) machine for converting electrical energy into mechanical energy (2) known as the dry end of the filter pump; it drives the impeller, which moves the water

MOVABLE BULKHEAD: a movable end wall that allows multipurpose usage

MULTIPORT VALVE: (1) 4 or 6 position valve combining the functionality of several valves into one unit, revolutionizing pool plumbing (2) also called a rotary-type backwash valve; 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 

NATADEK: PVC/polyester composite designed for use as a resilient, comfortable and long lasting decking or flooring for aquatic environments 

NATATEC Membrane Systems: versatile and durable lining system for the swimming pool shell; made from flexible PVC material, it limits maintenance, extends the life span of the pool and ensures that the pool is watertight

NORYL: brand name for a thermoplastic resin used in the manufacture of certain pump components and various other pool equipment fittings

ON-GROUND POOLS: see above ground pools

ORP: (1) exudation reduction potential (2) measurement of a body of water's ability to oxidize contaminants; measured with an electrode and an electronic meter (3) an indication of the sanitizing level or degree of safety from disease in the water; measured in millivolts with the accepted minimum level being 650 mV (millivolt)

PATHOGENIC ORGANISM: organism that causes disease

PERIMETER SYSTEM: see recirculating system

PERMANENT MEDIUM FILTER: uses sand or other medium that does not require replacement

PETCOCK: manually operated faucet or valve for draining liquids or releasing air pressure; air-relief valve on a filter is an example

PLASTER: mixture of white cement and white marble dust used as an interior finish, which can be tinted and colored applied to gunite or shotcrete pools or spas

PLUNGER: sliding disc assembly that changes valve position in a push-pull valve

PRECOAT: depositing diatomaceous earth (D.E.) onto the filter grids or elements

PRESSURE CHECK: (1) test for the rate of water flow (2) a test for leaks in plumbing by placing a line in question under pressure and waiting for the pressure to drop

PRESSURE DIFFERENTIAL: difference in the amount of water pressure being exerted on two parts of a hydraulic system, such as the incoming vs. the outgoing water through a filter

PRESSURE GAUGE: device indicating pressure in a filter system

PRESSURE SIDE: (1) return side of the plumbing (2) section from the pump impeller toward the pool

PRESSURE 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

PSI: pounds per square inch

PUMP: motor-powered mechanical device that creates pressure and water flow to permit filtration, heating and water circulation; pools usually use a centrifugal-type pump

PUMP CAPACITY: volume of liquid a pump is capable of moving during a specified period of time; usually gallons per minute (gpm)

PUMP CURVE: (1) also called a pump performance curve (2) graph that represents a pump's water flow capacity at any given resistance

PUMP STRAINER: lint and hair trap on the suction side of the pump to remove debris with a minimum of water flow restriction

PUSH-PULL VALVE: two-position valve used for backwashing sand or DE filters

PVC: (1) polyvinyl chloride (2) used to make flexible and rigid PVC pipe