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 ORGANIC
 
(chemical related) 
Refers to volatile, combustible and sometimes biodegradable chemical compounds 
containing carbon atoms bonded together with other elements. The principal 
groups of organic substances found in water are proteins, carbohydrates, fats 
and oils. See organic waste.
 ORGANIC WASTE  
(chemical related)  
Also called swimmer or bather waste - All of the soap, deodorant, suntan lotion, 
lipstick, makeup, cologne, body oils, sweat, spit, urine, etc., brought into the 
water. They also form chloramines, which are foul-smelling and body irritants. 
Requires large amounts of chlorine or non-chlorine shock to destroy.
 ORP  
(chemical related)  
An abbreviation for oxidation reduction potential. It is a measurement of a body 
of water's ability to oxidize contaminants. Measured with an electrode and an 
electronic meter. It is 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).
 OTO
 
(chemical related) 
Abbreviation for orthotolidine. A chemical reagent used to test the total 
chlorine level in pool and spa water. It does not measure free available 
chlorine. See DPD.
 OVER-ACID
 
(chemical related) 
An incorrect term used to describe water that is acidic or water that has a pH 
lower than 7.2.
 OVER-DRAIN Also called a 
diffuser or distributor - An internal sand filter device that evenly distributes 
influent pool water over the sand filter bed.
 OXIDATION
 
(chemical related) 
To rid the water of ammonia, nitrogen com- pounds and swimmer waste (organic 
compounds). These organic compounds disable chlorine, are body irritants and 
have a foul smell. Removal is accomplished by super chlorination or by shock 
treating with a non-chlorine oxidizer.
 OXIDIZER
 
(chemical related) 
A non-chlorine shocking compound that removes or destroys built-up contaminants 
and chloramines in pool water without raining chlorine levels as required when 
"super chlorinating."
 OZONE
 
(chemical related) 
A gaseous molecule comprised of 3 atoms of oxygen. It is generated on site from 
air oxygen and used for oxidation of water contaminants.  
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