LaMotte Pool & Spa Owner's Handbook - Manual (Page 9)

There are also non-chlorine shocks available, such as potassium
monopersulfate and sodium dipersulfate. These will eliminate combined
chlorine. Keep in mind that these non-chlorine shocks are oxidizers only,
not sanitizers. Chlorine or bromine must be added to maintain an
adequate level of sanitizer.
Stabilizing your Free Chlorine
In an outdoor swimming pool, the use of a chlorine stabilizer (cyanuric
acid) is usually recommended to reduce the degradation of free chlorine by
sunlight. Cyanuric acid acts like a shield for chlorine from ultraviolet
light. It can be added by itself, usually at an initial dose of 30-40 ppm,
or cyanuric acid can be added as part of a chlorine compound. Two forms
of chlorine that contain cyanuric acid are known as Sodium
Dichloro-s-triazinetrione Dihydrate (dichlor) and
Trichloro-s-triazinetrione (trichlor). When these are added to water, they
form free chlorine and cyanuric acid. Since trichlor has more active
stabilizer and chlorine it usually costs more.
There are three common unstabilized forms of chlorine. They are sodium
hypochlorite (liquid bleach), calcium hypochlorite(cal-hypo) and lithium
hypochlorite. These are normally used for indoor pools, superchlorination
treatments or when cyanuric acid levels are too high.
Chlorine Demand
The National Spa and Pool Institute defines chlorine demand as “the
amount of chlorine that will be consumed by readily oxidizable impurities
in water”. In simpler terms, if a 3 ppm dosage of chlorine is added and is
promptly tested to find only 2 ppm is on hand, the water had a 1 ppm
demand. Many things contribute to chlorine demand such as bacteria,
organics (like dirt and leaves), fertilizers (including nitrate and
phosphate), and bather wastes. When opening a pool in the spring or after
a heavy storm, expect higher than usual chlorine demands. Once the
demand is met, the remaining free chlorine residual is there to take care of
the additional demand.
7
The ideal free chlorine range for pools is 1-3 ppm
and for spas is 2-4 ppm.
IDEAL
RANGE!