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Water
Chemistry For Swimming Pools
Proper water chemistry is essential to
maintaining safe and consistent swimming pool operation. Chemicals
used
in swimming pools include: Disinfectants to destroy harmful or otherwise
objectionable organisms;
Alkalinity and pH Adjusters to maintain a
consistent acid-base relationship and acid buffering capacity; Chlorine
Stabilizer to prevent unnecessary loss of chlorine; Algicide to kill and prevent
algae, and Filter Aids to help remove
foreign material. Following is a
discussion of various factors which affect water chemistry, how they affect
swimming
pools and hot to use pool chemicals to restore a properly balanced water
chemistry.
pH - Why you need to Balance
It!!!!
pH Is the single most important element in
swimming pool water chemistry. It affects every other chemical
balance
in pool water.
pH is a measure of hydrogen ion (H+)
concentration in water. It indicates the relative acidity or basicity
of pool water. pH is measured on a scale of 0 (strong acid) to 14 (strong
base) with 7 being
the neutral pH.
In pools a slightly alkaline pH of 7.4 to
7.6 is most desirable because this range is most comfortable
to the human eye
and provides for optimum use of free chlorine while maintaining water that is
not
corrosive or scale forming.
If pH is too low (below 7)
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Water becomes acidic
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Chlorine residuals dissipate rapidly
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Eye irritation occurs
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Plaster walls are etched
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Metal fittings, pump impeller, heater core
may corrode
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Dissolved metals may leave stains on walls
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Rapids loss of alkalinity
If pH is too high( above 8)
pH adjustment
To avoid the problems listed above, pH
must be maintained between 7.2 and 7.8. The
most desirable level for pH
is between 7.4 and 7.6 If pH is too low - run alkali demand test
if
available. Raise pH by adding soda ash (sodium carbonate). Never add
more than 2 LBS
10,000 gallons in a single treatment. Be sure the pump
is running when chemicals are added.
Allow to recirculate then retest to
determine if further treatment is necessary. Caustic soda
(sodium
hydroxide) is sometimes used with chemical feed pumps to raise pH. If
problems with
low pH persist, it may be necessary to raise total alkalinity
to stabilize the pH.
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