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.