| CALCIUM 
CARBONATE 
(chemical related)  
Crystalline compounds formed in swimming pool and spa water when the calcium, pH 
and total alkalinity levels are too high. Once formed, the crystals adhere to 
the plumbing, equipment, pool walls and bottom. These crystals are better known 
as scale.
 CALCIUM CHLORIDE  
(chemical related)  
A soluble white salt used to raise the calcium or total hardness level in the 
pool or spa.
 CALCIUM HARDNESS  
(chemical related)  
The calcium content of the water. Calcium hardness is sometimes confused with 
the terms water hardness and total hardness. Too little calcium hardness and the 
water is corrosive. Too much calcium hardness and the water is scale forming. 
One of the basic water tests necessary to determine water balance. Minimum level 
is 150 ppm. Ideal range is 200 to 400 ppm.
 CALCIUM HYPOCHLORITE   
(chemical related)   
Also called 'Cal Hypo'. A compound of chlorine and calcium used as a 
disinfectant, sanitizer, bactericide, algaecide and oxidizer in swimming pool 
and spa water. It is available as a white granular material usually used for 
super chlorination or it is available as tablets used in a feeder for regular 
chlorination. It usually contains 65% available chlorine.
 CARTRIDGE A replaceable 
porous element made of paper or polyester used as the filter medium in cartridge 
filters.
 CARTRIDGE FILTER A pool or 
spa water filter that uses a replaceable porous element made of paper or 
polyester.
 CENTRIFUGAL PUMP A 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.
 CHECK VALVE A mechanical 
device in a pipe that permits the flow of water or air in one direction only.
 CHELATE
 
(chemical related) 
(Pronounced KEY-late) - also called sequester - It is the process of preventing 
metals in the water from combining with other components in water to form 
colored precipitates that stain the pool walls and bottom or produce colored 
water.
 CHELATED COPPER  
(chemical related)  
Copper algaecides that contain a special ingredient to prevent the copper from 
staining the pool walls and bottom or producing colored water.
 CHEMICAL FEEDER  
(chemical related)  
Any of several types of devices that dispense chemicals into the pool or spa 
water at a predetermined rate. Some dispense chlorine or bromine while others 
dispense pH-adjusting chemicals.
 CHLORINE NEUTRALIZER  
(chemical related)  
A chemical used to make chlorine harmless. Used in test kits to counteract the 
bleaching effect of the chlorine or bromine in order to increase the accuracy of 
pool water tests. Sold as chlorine and bromine neutralizer, it is used to 
destroy excessive amounts of chlorine or bromine, so the high levels will not 
affect swimmers.
 CHLORAMINES
 
(chemical related) 
Undesirable, foul-smelling, body-irritating compounds formed when insufficient 
levels of free available chlorine react with ammonia and other 
nitrogen-containing compounds (swimmer and bather waste, fertilizer, 
perspiration, urine, etc.). Chloramines are still disinfectants, but they are a 
much weaker, ineffective form of chlorine. Chloramines are removed by super 
chlorination or shock treating.
 CHLORINATOR
 
(chemical related) 
A mechanical or electrical device for dispensing chlorine at a controlled rate. 
Most often a canister or floater filled with tablets of chlorine.
 CHLORINE
 
(chemical related) 
A term used to describe any type of chlorine compound used as a disinfectant in 
swimming pool and spa water or to kill, destroy or control bacteria and algae. 
In addition, chlorine oxidizes ammonia and nitrogen compounds (swimmer and 
bather waste).
 CHLORINE DEMAND  
(chemical related)  
The amount of chlorine necessary to oxidize all organic matter (bacteria, algae, 
chloramines, ammonia and nitrogen compounds) in the pool or spa water.
 CHLORINE ENHANCER  
(chemical related)  
A chemical compound that when used in conjunction with chlorine makes the 
chlorine perform better as an algaecide.
 CHLORINE gas  
(chemical related) 
This is the most pure form of chlorine and can only be applied to pools by a 
trained professional. It is not an appropriate sanitizer for spas
 CHLORINE GENERATOR  
(chemical related)  
An electrical device that generates chlorine from a salt solution in a tank or 
from salt added to the pool water.
 CHLORINE LOCK  
(chemical related)  
This is a term that implies that an over- abundance of cyanuric acid (stabilizer 
or conditioner) in the water would cause the chlorine to be all "locked up." 
This is not true.
 CHLORINE RESIDUAL  
(chemical related)  
The amount of chlorine left in the pool or spa water after the chlorine demand 
has been satisfied.
 CIRCULATION SYSTEM  
An arrangement of mechanical equipment or components, connected by piping to a 
pool or spa in a closed circuit. The function of a circulation system is to 
direct water from the pool or spa, causing it to flow through the various system 
components for purposes of clarifying, heating, purifying, and returning the 
water back to the original body of water.
 CLARIFIER
 
(chemical related) 
 Also called coagulant or flocculant - A chemical compound used to gather 
(coagulate or agglomerate), or to precipitate suspend- ed particles so they may 
be removed by vacuuming or filtration. The are two types; inorganic salts of 
aluminum (alum) or water- soluble organic polyelectrolytes.
 CLARITY
 
(chemical related) 
 The degree of transparency of the water.
 COAGULANT
 
(chemical related)  
An organic polyelectrolyte used to gather (coagulate) suspended particles in the 
water.
 COLORMETRIC TEST 
(chemical related) 
A test for chlorine, bromine and pH where the reagent causes a change in color 
when reacting with the specified chemical.
 COMBINED CHLORINE  
(chemical related)  
Undesirable, foul-smelling, body-irritating compounds formed when insufficient 
levels of free available chlorine react with ammonia and other 
nitrogen-containing compounds (swimmer and bather waste, fertilizer, 
perspiration, urine, etc.). Combined chlorine is still a disinfectant, but it is 
a much weaker, ineffective form of chlorine.
 CONDITIONER
 
(chemical related) 
Chemically, conditioner is cyanuric acid. It slows down the degradation of 
chlorine in the water by sunlight.  
 COPING The 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 pre-cast, 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.
 COPPER
 
(chemical related) 
It is one of nature's elements. It is also used for various parts of equipment 
and plumbing in swimming pools and spas. Corrosive water caused by misuse of 
chemicals, improper water balance, or placing trichlor tablets in the skimmer 
can cause copper to be dissolved from the equipment or plumbing and deposit the 
precipitates on hair, finger- nails or pool walls. High levels of copper also 
cause green water. Copper is also used as an algaecide. Maximum level is about 
0.2 ppm.
 COPPER ALGAECIDE  
(chemical related)  
A chemical compound that contains the element copper. Copper sulfate was one of 
the original copper algaecides. Too much copper in the water can cause 
green-colored stains. Newer copper algaecides contain an ingredient that 
prevents the copper from staining but does not affect copper's ability to kill 
algae. These special copper algaecides are called chelated copper algaecides.
 CORROSION
 
(chemical related) 
The etching, pitting or eating away of the pool or spa or equipment. Caused by 
improper water balance, misuse of acid or acidic products or from soft water.
 COUPLING A plumbing 
fitting that is used to connect two pieces of pipe.
 COVER, HARD-TOP A 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 A 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, THERMAL An 
non-transparent insulating flotation cover used to help prevent evaporation and 
heat loss from pools and spas.
 COVER, WINTER A 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.
 CYANURIC ACID  
(chemical related)   
Also called conditioner or stabilizer - Chemically, conditioner is cyanuric 
acid. It protects chlorine in the water from being destroyed by sunlight. 
 
 
 |