Natare Terminology

ACRYLIC

thermoplastic sheet formed into a mold to make a spa or related equipment; it is first heated and then vacuumed onto the mold

AIR BLEEDER ASSEMBLY

located on the top of the filter, sometimes accompanied by a pressure gauge, the bleeder is opened to release air trapped in the filter

AIR BLOWER

mechanical device that forces air through holes in the floor, bubbler ring or hydrotherapy jets in a spa

AIR-RELIEF VALVE

1. brass or plastic, manually operated valve located at the top of a filter tank for relieving the pressure inside the filter and for removing the air inside the filter (called bleeding the filter)
2. sometimes called a pressure-relief valve

AUTOMATIC POOL CLEANER

device, which agitates or vacuum debris from the walls and floor of the pool automatically

Automatic Surge

device incorporated into a stainless steel perimeter

AWS Systems

Above-ground (On-ground) pools

pools that are portable and removable; a frame that is located entirely above ground and can be disassembled

Access Equipment

variety of equipment designed to facilitate entrance and egress from a pool; may include ladders, lifts, steps or boards

BACKFILL

repositioning of the soil after construction of a pool

BACKFLOW

backing up of water through a pipe in the direction opposite to normal flow

Backstroke Flags

colorful vinyl pennants spaced and sized to meet competitive swimming requirements; generally placed five yards (short coarse) or five meters (long course) from the end of the pool; they enable backstrokers to execute a backstroke turn more efficiently by counting their strokes

Backwash

reversing flow of water through the filter to clean the elements and filter medium

Backwash Cycle

time needed to backwash (clean) the filter and its components using a reverse flow of water

BALL VALVE

device with a hollowed out ball inside which can be turned with an external handle to decrease or increase flow

BLOWER

electrical device that produces a continuous rush of air to create the optimal bubbling effect in a spa, hot tub or whirlpool; it is usually plumbed with the hydrotherapy jets or to a separate bubbler ring

BOOSTER PUMP

secondary to the filter pump, a booster pump is used to power an automatic pool cleaner such as Polaris or Letro

BTU

1. abbreviation for British Thermal Unit; the amount of heat necessary to raise 1 lb. of water 1 degree Fahrenheit
2. a unit of measurement for the use of gas by a gas appliance; pool heaters are rated by their consumption

COPING

cap or top lip on the pool or spa wall that provides a finished edge around the pool or spa; it can be formed, cast in place or precast, or prefabricated of extruded aluminum or rigid vinyl; it may also be part of the system that secures a vinyl liner to the top of the pool wall

COUPLING

plumbing fitting designed to join two pieces of pipe

COVER, HARD-TOP

cover used on pools, spas and hot tubs that rests on the lip (coping) of the pool or spa deck – not a flotation cover; used as a barrier to swimmers and bathers, and for maintenance and thermal protection

COVER, SOLAR

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 wine-borne debris from entering the water

COVER, WINTER

cover that is secured around the perimeter of a pool, spa or hot tub that provides a barrier to bathers and debris when the pool, spa or hot tub is closed for the season

Cover, Thermal

cover that retains heat and prevents water evaporation

CARTRIDGE FILTER

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

CENTRIFUGAL PUMP

pump consisting of an impeller fixed on a rotating shaft and enclosed in a casing or volute and having an inlet and a discharge connection; the rotating impeller creates pressure in the water by the velocity derived from the centrifugal force

CIRCULATION SYSTEM

"circuit" of plumbing which continuously carries the water out of the pool, through the pump & filter, and returns it to the pool

CLARITY

degree of transparency of waterCONDUIT

D. E. FILTER (Diatomaceous Earth Filter)

filter designed to use diatomaceous earth (D.E.) as the filter medium; the D.E. is added through the skimmer with the pump on, which takes the D.E. and deposits it on a grid; the D.E. then becomes the filter medium

DECK SURFACING

DECKS

areas immediately adjacent to a pool or spa that are specifically constructed or installed for use by bathers for sitting, standing or walking

DIATOMACEOUS EARTH

1. also called D.E.
2. white poder composed of fossilized skeletons of one-celled organisms called diatoms; the skeletons are porous and have microscopic spaces; the powder is added through the skimmer with the pump on and deposits itself on a grid; the powder then becomes the filter medium

Diatomaceous Earth Filter

see D.E. Filter

DIFFUSER

1. porous plate, tube or other device through which air is forced and divided into minute bubbles for diffusion in the water
2. an over drain on a sand filter
3. used on a closed-face impeller on a pump to concentrate water flow to the center of the impeller

DISSOLVED SOLIDS

1. also called TDS or total dissolved solids
2. a measure of the total amount of dissolved matter in water; examples are calcium, magnesium, carbonates, bicarbonates, sodium, chlorides and metals; high levels can cause corrosion, colored water or salty taste; maximum level is usually 2500 ppm for pools; maximum level for spas is 1500 ppm over starting level

Diving Board

see springboard

Drain (vacuum to waste)

this useful setting allows you to vacuum 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

DRAIN

1. plumbing fitting installed on the suction side of the pump in pools, spas and hot tubs
2. sometimes called the main drain, it 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

EFFLUENT

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

plumbing fitting shaped at a 90-degree or a 45-degree angle usually made of metal, PVC or plastic

ESCUTCHEON PLATE

ornamental shield, flange or border used around a pipe, plumbing fitting, grab rail or light

FILTER POWDER

common name for diatomaceous earth (D.E.), used as the filter medium in a diatomaceous earth filter

Foot Bath

Flow Rate

volume of liquid flowing past a given point in a specific time period, expressed in gallons per minute or hour

Flow Meter

measuring device that determines the gallons per minute of water flow through a pool re-circulation system

FIREMAN’S SWITCH

mechanical switch located inside the time clock, which opens a circuit and shuts off the heater 10 or 15 minutes prior to shutting off the water circulation pump, allowing the heater to cool down; this helps reduce lime buildup in the heat exchanger

FILTRATION RATE

rate of water pumped through a filter, in gallons per minute (gpm)

FILTER SEPTUM

portion of the filter element consisting of cloth, wire screen or other porous material on which the filter medium or filter aid is deposited; nylon grid on a D.E. filter is the septum

Filter Sand

sharp silica or quartz particles graded for uniform size and used as a filter medium

FILTER ROCK

graded, rounded rock and/or gravel used to support the filter medium; usually used with rapid-rate sand filters

FILTER PUMP

device that pulls water from the pool and pushes it through the filter on its way back to the pool

FILTER MEDIUM

finely graded material, such as sand, diatomaceous earth, polyester fabric or anthracite coal that removes suspended particles from water passing through it

filter latErals

see underdrain

Filter Element

porous component in the filter tank that removes particles and other suspended wastes from water before its re-circulated back to the pool

FILTER CYCLE

1. operating time between cleaning or backwashing cycles of a filter
2. amount of time the filter has water flowing through it each day expressed in hours

FILTER CARTRIDGE

replaceable porous element made of paper or polyester used as the filter medium in cartridge filters

FILTER AREA

total surface area of the filter medium that is exposed to the flow of water from the pump, expressed in square feet

FILTER AID

chemical compound added to the water or to the filter that allows the existing filter to become more efficient; examples are alum, water clarifiers and D.E. (diatomaceous earth)

Filter

mechanical device for straining suspended waste particles from the pool as water circulates through a porous substance called a filter medium; refers to the complete mechanism including all components; the three types of filters used in pools and spas are sand, cartridge and D.E. (diatomaceous earth)

FIBERGLASS

fine spun filaments of glass which are available in a rope or mat form; when used in a process with polyester resins, catalysts and hardeners can be formed or molded into pools, spas and related shapes

Face Piping

piping, with all valves and fittings, which is used to connect the filter system together as a unit; this includes all valves and piping necessary for the filter plant to perform the functions of filtering or backwashing, either by the plant as a whole or any unit operating singly

Gelcoat

colored polyester-resin liquid applied to a mold during the manufacturing of fiberglass pool or spa shells

GPD

gallons per day

GPH

gallons per hour

GPM

gallons per minute

GRAB RAIL

1. also called hand rail
2. tubular steel or plastic device that can be gripped by swimmers or bathers for the purpose of steadying themselves; usually located near the steps in the pool

GREEN HAIR

condition caused by too much copper, not chlorine in the pool water; copper may get into the water by the bad practice of placing trichlor tabs in the skimmer; this acidic product will cause low-pH water, which in turn will dissolve metals in the equipment; the dissolved metal (usually copper) then stains hair, fingernails and, eventually, pool walls; keeping the pH too low or misusing acid can also cause it

GROUND-FAULT CIRCUIT-INTERRUPTER

interrupts (de-energizes) the electrical circuit whenever it detects the presence of excess electrical current going to ground (usually 1/40th of a second and 5/1000th of an ampere)

Gunite

concrete and sand mixture sprayed onto a reinforced steel form to create a pool shell; dry mixture of cement and sand is mixed with water at the "gun or spraying device", hence the name

GUTTER

1. overflow trough at the edge of the pool through which floating debris, oil and other "lighter-than-weight" items flow; pools with gutters usually do not have skimmers
2. also called a perimeter or recirculation system

GAS VALVE

electronic valve in the pool heater that directs gas flow from the meter to the pilot and the burner tray

HAND RAIL

see grab rail

HAND SKIMMER

screen attached to a frame which is then attached to a telepole used to remove large floating debris, such as leaves and bugs, from the water’s surface

HEAT EXCHANGER

1. device located inside the heater providing for the transfer of heat from the heat source to the water; this is usually a series of metallic tubes with fins located just above the flames
2. set of 8 or 10 ribbed copper tubes that absorb the heat produced below it and transfer it to the water cycling through its tubes

HEAT PUMP

using a cooling coil, it removes heat from the air while the condenser coil transfers it to the water being cycled through the pump

HEATER

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

Hot Tub

a circular, wooden vessel with the sides and bottom formed separately and joined together by hoops, bands or rods; filled with heated and circulated water

HYDROJET

fitting in the pool or spa on the water return line from the equipment that blends or mixes air and water, creating a high-velocity, turbulent stream of air-enriched water

HYDROSTATIC PRESSURE

force involving built up ground water, which creates upward pressure beneath the pool shell

HYDROSTATIC RELIEF VALVE

fitting(s) installed in the floor of the pool designed to manually or automatically release hydrostatic pressure beneath the pool by allowing ground water into the pool

Hydrotherapy Spa

unit primarily for therapeutic use to ease stress, muscle strains and other physical problems

Influent

1. water flowing into a filter, pipe, pool, chemical feeder or other space; water going into the pump is called in influent, while water leaving the pump is called the effluent
2. the water coming into and up to the impeller from the suction lines; these pipes are under vacuum pressure

In-ground pools

are partially or completely installed in the ground

INLET

fitting in the pool or spa on the water return line from the equipment that water returns to the pool

IMPELLER

rotating member of a pump; its action creates the flow of water

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

LIGHT NICHE

area in a pool or spa that house the underwater light

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

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

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

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

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)

PVC MEMBRANE LINER

PRESSURE SIDE

1. return side of the plumbing
2. section from the pump impeller toward the pool

PVC

1. polyvinyl chloride
2. used to make flexible and rigid PVC pipe

PUSH-PULL VALVE

two-position valve used for backwashing sand or DE filters

Pump Strainer

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

PUMP CURVE

1. also called a pump performance curve
2. graph that represents a pump’s water flow capacity at any given resistance

PUMP CAPACITY

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

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

Psi

pounds per square inch

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

PRESSURE GAUGE

device indicating pressure in a filter system

PATHOGENIC ORGANISM

organism that causes disease

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 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

PRECOAT

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

PLUNGER

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

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

PETCOCK

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

Permanent Medium Filter

uses sand or other medium that does not require replacement

Perimeter System

see recirculating system

RATE OF FLOW

quantity of water flowing past a designated point within a specified time period, measured in gallons per minute (gpm)

Recirculating System

1. system of pipes, pumps, filters that allows water to be taken from the pool, filtered, treated and returned to the pool
2. also called a gutter or perimeter system

Recreational Surfacing

REGLET

.. A horizontal slot, formed or cut in a concrete, tile, masonry or block wall into which the top edge of Natatec PVC membrane or NataDek flooring or other material can be inserted and anchored.

Residential

pools for home use rather than for public or commercial use

reverse circulation

pool-water circulation system; water is taken from the surface of the pool and returned through inlets at the bottom of the pool

SOLAR SYSTEM

black mats of miniature plastic tubes through which water is pumped, absorbing the heat as it passes through; these mats are roof mounted with up and down plumbing connecting it

Swimmer Load

the number of persons in the pool area at any given moment, or any stated period of time

SUSPENDED SOLIDS

insoluble solid particles that either float on the surface or are in suspension in the water, causing turbidity

SURGE CONTROL WEIR

1. part of a stainless steel gutter that controls the operating level of the pool at quiescent (low or no-use periods) to ensure that adequate in-pool surge is available when swimmers enter the pool
2. eliminate the need for a surge control tank

SURGE CONTROL TANK

1. large tank constructed near or immediately adjacent to the edge of the pool that incorporates a modulating valve on the main drain to maintain a normal operating level well below the level of the pool in quiescent operation
2. the difference between the pool level and the operating level in the surge tank is the surge capacity, which is normally required to be approximately 1 to 2 gallons per square foot of pool surface area

SURGE CONTROL GATE

device in a perimeter gutter system that controls the amount of water coming into the gutter from the weir openings in the face of the gutter

SPS Systems

SPRINGBOARD

1. also called diving board
2. recreational mechanism for entering a swimming pool consisting of a semi-rigid board that derives its spring from a fulcrum mounted below the board and attached to the deck

SPA

filtered, hot water vessel with hydrotherapy jets and air induction; can be portable or installed permanently

SOURCE

the origination of electrical power; the source for a filter pump (load) is probably a timer clock

SOURCE WATER

see make-up water

Solar Heating System

panels or coils of plastic or metal through which water passes to increase the temperature from the sun’s heat

SLURRY

water or a liquid containing a high concentration of suspended solids

SKIMMER WEIR

1. part of a skimmer that adjusts 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
2. the weir also prevents debris from floating back into the pool when the pump shuts off

SKIMMER NET

attached to a telescopic pole, a leaf rake is a very useful tool in keeping the pool clean

SKIMMER BASKET

removable, slotted basket or strainer placed in the skimmer on the suction side of the pump; beneath the lid, the basket strains debris, as the first line of defense in filtering the water

Skimmer

SILT

soil particles having diameters between 0.004 and 0.062 mm

SAND FILTER

filter using sand or sand and gravel as the filter medium; the pump diffuses water over the top of the sand bed, and forces it through the sand and into the laterals on the bottom

SHOTCRETE

mixture of sand and cement sprayed onto contoured and supported surfaces to build a pool or spa; plaster is applied over the shotcrete; shotcrete is premixed and pumped wet to the construction site

SEPTUM

portion of the filter element consisting of cloth, wire screen or other porous material on which the filter medium or filter aid is deposited; the nylon grid on a D.E. filter is the septum

SAND

usually refers to the filter medium used by a sand filter; the grade most often specified by filter manufacturers is grade No. 20 with a particle size of 45 to 55 mm

TIME CLOCK

mechanical or electrical device that automatically controls the periods that a pump, filter, heater, blower, automatic pool cleaner or other electrical devices are on or off

TURNOVER

1. also called turnover rate
2. number of times a quantity of water equal to the total capacity of the pool passes through the filters in a stated time; usually in turnovers per day; pool capacity in gallons, divided by pump flow rate in gallons per minute (gpm), divided by 60 minutes in 1 hour, will give hours for 1 turnover

TEE

TELEPOLE

long-handled aluminum pole, which extends in length to which various pool-cleaning tools, such as brushes or vacuums, can be attached

UNDERDRAIN

1. lower collection system in a filter, which directs filtered water back toward the pool
2. distributes water in reverse during backwashing
3. also called filter laterals or lower collection system

UNDERWATER LIGHT

fixture designed to illuminate a pool or spa from beneath the water’s surface

VACUUM

1. one of several types of suction devices designed to collect dirt from the bottom of the pool; some discharge dirt and water into the filters, some discharge to waste, and some collect debris in a porous container, allowing water to return to the pool; some are self-propelled; others must be pushed or pulled across the pool
2. low-pressure condition created in the suction line
3. cleaning process of sucking leaves, algae and debris from the pool floor

VALVES

device placed in the plumbing line, which restricts or obstructs water flow to create desired hydraulics, or may permit flow in one direction only

VENTURI

1. 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 hydrotherapy jet draws air in and mixes it with the water using this principle
2. increasing water velocity by restricting pipe size

VINYL LINER

WATER CLARIFIER

1. also called coagulant or flocculants
2. a chemical compound used to gather (coagulate or agglomerate) or to precipitate suspended particles so vacuuming or filtration may remove them; there are two types

WEIR

see skimmer weir

Winterizing

procedure for protecting pools, spas and hot tubs from freezing conditions; includes physical and chemical protection

WATER CLARIFIER

1. also called coagulant or flocculants
2. a chemical compound used to gather (coagulate or agglomerate) or to precipitate suspended particles so vacuuming or filtration may remove them; there are two types:  inorganic salts of aluminum (alum) and other metals, and water-soluble organic polyelectrolytes

WEIR

see skimmer weir

Winterizing

procedure for protecting pools, spas and hot tubs from freezing conditions; includes physical and chemical protection