Glossary of Pool Terms

a

Acid

A chemical, which lowers the pH when added to the water

Acid Demand

Amount of acid required to lower pH and total alkalinity of pool water to correct level

Algae

Microscopic aquatic plant life, which can grow on pool surfaces or float freely in the water. Though harmless, algae discolor the water and indicate improper sanitation.

ALGAECIDE

Chemical used to kill or inhibit growth of algae

ALKALINITY

Various chemicals and salts in the pool water that increase pH

AVAILABLE CHLORINE

Free or combined chlorine used to disinfect pool water

B

BACKWASHING

Cleaning pool filter by reversing water flow

BROMINE

Chemical used for disinfecting spas mainly (in same family as chlorine)

C

CAVITATION

Water is boiling in a pump. The flow of water from the suction lines is restricted, which causes a vapor lock at the impeller. Commonly recognized by a rumbling noise in the pump.

CHLORAMINE

Chemical compound of nitrogen and hydrogen that combines with free chlorine in pool water. Chloramine causes burning eyes, skin irritation, and chlorine odor.

CHLORINE

Chemical used for disinfecting swimming pools

CHLORINE DEMAND

Amount of chlorine required to destroy bacteria in pool water

CHLORINE RESIDUAL

Amount of chlorine remaining in pool water after chlorine demand has been satisfied

CORROSION

Chemical reaction that causes deterioration of metal

CYANURIC ACID

(conditioner/stabilizer) acid used in pool water to prevent chlorine loss

D

DIATOMACEAOUS EARTH (DE)

White powder that is manufactured from microscopic skeletons of diatoms

DISSOLVED SOLIDS

Calcium, copper salts, magnesium and other minerals that are suspended in water

DPD

Chemical reagent that reacts with active chlorine/bromine and turns the water sample pink

F

FREE CHLORINE

Basic chlorine, not combined with any other chemicals, allowing it to be released immediately for disinfecting. This is usually the kind of chlorine used to superchlorinate.

H

Hardness

Measurement of dissolved solids in water

M

Muriatic acid

Dilute solution of hydrochloric acid used to lower alkalinity

O

ORTHOTOLIDINE (OTO)

Chemical reagent that reacts with total chlorine/bromine, and turns water sample yellow

P

pH

Used to describe acid/alkaline balance in pool water. A pH of 7 is neutral. pH values below 7 are acidic. pH values above 7 are basic. The recommended pH for swimming pool water is 7.2 to 7.8. Never allow pH to drop below 7.0 or go above 8.0.

PHENAL RED

Chemical reagent used to measure pH

PPM

Parts per million, the accepted measurement of a quantity of substance in water

R

REAGENT

Liquid or powder chemicals used to test concentrations of specific compounds in water

RESIDUAL

Amount of a compound existing in water, usually expressed as PPM

S

SCALE

Mineral deposits formed on pool surfaces, inside piping and on the filter as a result of high calcium hardness and high pH

SODA ASH

Sodium carbonate used to adjust the total alkalinity by increasing the pH

SUPERCHLORINATION

Heavy dose of chlorine added to pool water to “burn out/shock” nitrogen compounds when bacteria, algae or chloramine build-up cannot be reduced by normal treatment

T

TOTAL ALKALINITY (TA)

Measurement of alkaline chemicals in water. TA acts as a pH buffer. Too high of a TA prevents easy adjustment of pH. Low TA causes pH to change and fluctuate widely. Proper pool TA is 100 to 125 ppm.

TOTAL DISSOLVED SOLIDS

Total of dissolved material in the water. High total dissolved solids in pool water (over 1500 ppm) can cause poor sanitizer efficiency, cloudy water and odors.

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