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When any type of chlorine is added
to water, it usually forms hypochlorous acid (HOC1 the most powerful
killing form of chlorine in water) and a hypochlorite ion (OC1-), a
relatively weak form of chlorine in water. The percentage of HOCL and OC1-
is determined by the pH of the water. As the
pH goes up, less of the chlorine
is in the killing form and more of the chlorine is in the weaker form .
The total of HOC1 and OCI- is the free available chlorine.
Chlorine can
combine with ammonia and nitrogen compounds in the water to form
chloramines, sometimes called combined chlorine. By combining with ammonia
and nitrogen, free chlorine in the water is disabled. Chloramines are 60
to 80 times less effective than free chlorine. Chloramines are formed any
time ammonia and nitrogen are in the water. Some of the ammonia and
nitrogen compounds are introduced into the water by swimmers and bathers
in the form of perspiration, urine, saliva, sputum and fecal matter. An
active swimmer sweats one pint per hour. The average person sweats three
pints per hour in a heated spa. Ammonia and nitrogen compounds are also
introduced into the water by rain. Each drop of rain has some dissolved
nitrogen from our atmosphere and from automobile emissions.
Chloramines smell bad. This is the smell most often associated with
pools and spas in health clubs and YMCAs. Chloramines are eye and skin
irritants, and they can cloud the water.
Chloramines can be removed from the water by the following three
methods:
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By adding a mega-dose of chlorine. Usually 3 to 6 times more
chlorine than a normal dose is added to the water, or the level of
chlorine is raised to 5 to 10 ppm and held there for 4 hours. This is
called super chlorination. To remove chloramines, the ratio of chlorine
to ammonia must be at least 7.6 to 1. If this ratio is not obtained,
then more chloramines will be produced. Swimmers and bathers should not
enter the water until the level of chlorine has dropped to 3 ppm or
less.
- By adding a non-chlorine shock to the water. The most common
chemical used for this is potassium peroxymonosulfate. This "shocking"
requires the addition of one pound of shock for each 10,000 gallons of
pool water.
- By adding ozone to the water. If an
ozone generator is installed
and wired so that it comes on each time the pump comes on, then
oxidation of the ammonia and nitrogen compounds will take place on a
continuous basis. This eliminates the need for super chlorination or
shocking. Each time ammonia and nitrogen enter the ozonated water, they
are oxidized immediately.
Ozone oxidizes soap, deodorant, hair spray, cologne makeup, perfume,
body lotion, hand cream, sun tan lotion saliva and urine. In addition,
ozone kills all pathogenic bacteria, germs and virus. Ozone takes care of
the big job of oxidizing all these organic contaminants. Ozone frees up
the combined chlorine leaving the chlorine free to provide a residual.
Ozone ultimately enhances the performance of chlorine and
bromine.
Less chlorine or bromine will be needed to maintain a
residual.
Commonly, ozone reduces chlorine or bromine use by 50-90 percent. The
quality of water will be dramatically better with the combination of ozone
and chlorine or the combination of ozone and bromine than that with
chlorine and bromine alone. |