On-Ground Residential Pool:
Removable pool that is on the ground and also has an excavated area below the earth.
Organic Matter:
Perspiration, urine, saliva, suntan oil, cosmetics, lotions, dead skin and similar debris.
ORP (Oxidation Reduction Potential):
A measure of the oxidizing agents in water which serves as a relative measure of the desired "work value" of a pool sanitizer.
OTO (Orthotolidine):
A reagent which reacts with chlorine and bromine to produce specific colors on a test strip which measure the amount of chlorine or bromine in pool water.