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READY THE DIRECTIONS
CAREFULLY
For
sterilization of pool water chlorine is the most widely
accepted and used chemical. It is an efficient bactericide as
well as good algaecide when used properly. The amount of
chlorine required to maintain a pool in a safe sterilized
condition will vary depending upon several factors such as
water temperature, extent to which the pool is used, degree or
airborne contamination, sunlight exposure, and balance of
other chemicals and minerals present in the water.
It is a good practice to
maintain a free chlorine residual of between 0.3 and 0.6 ppm
(parts per million) in the water at all times. This is based
upon the use of chlorine without any stabilizing agent, such
as cyanuric acid. If a stabilizer is used, the chlorine
residual should be increased to at least 1.0 ppm.
Chorine plays another
important role in addition to its sterilizing action. During
the process of use of a pool there is an accumulation of
various nitrogen containing organic compounds in the water.
These nitrogen compounds tend to reduce the effectiveness of
chlorine as a germicide. However, when chlorine is added in
greater strength it will literally burn these undesirable
materials rendering them inactive. Because of this it is
important that a shock dosage of chlorine, 5 to 10 times the
normal dosage, be added once every few weeks when the pool is
not in use to burn out the nitrogen materials. This is
referred to as Shock Treatment or Break Point Chlorination.
Chlorine
Residual
(free available) is the reserve amount of active chlorine
present in the water available to immediately act upon
bacteria or algae contamination as it may occur. This residual
should be tested for daily, preferably in the morning before
the pool is in use. The chlorine residual test is made with
your water test kit. Two types of test kits are generally
accepted in the swimming pool industry, OTO and DPD. OTO
1.
(orthotolidine) upon the addition of a few drops of OTO
to a sample of pool water, a yellow color will develop in the
sample if there is any chlorine present. The amount of
chlorine is indicated by the intensity of the yellow and is
determined by comparison with calibrated color standards which
are a permanent part of the test kit. DPD (Diethyl-p-phenylene
diamine) with this type of test kit, a DPD chlorine tablet is
added to a sample of pool water, the amount of “free”
chlorine is indicated by comparison of the resultant color to
the color chart provided with the kit. To be assured of safe
water, the chlorine residual should be kept between 0.3 and
0.6 ppm (parts per million). If a chlorine stabilizer such as
cyanuric acid is used, the residual should be increased to at
least 1.0 ppm.
1.
pH. The balance between acidity and alkalinity
is referred to as pH. It is represented by numerical values
ranging from 1.0 to 14.0. A value of 7.0 indicates a neutral
condition, neither acid nor alkaline. Values below 7 represent
an acid condition increasing in intensity as the numerical
value decreases. Alkaline conditions are represented by values
above 7.0 increasing in strength as the numbers become
greater. The ideal pH for pool water is generally between 7.2
and 7.6.
a.
Balancing the pH. If the pH deviates too far
from the normal it should be adjusted.
b.
Low pH. When the pH drops below 7.2 it should be
adjusted upward by the addition of small quantities of soda
ash. Too low a pH causes skin and eye irritation and will
accelerate corrosion of pool equipment.
c.
High pH. If the pH rises above 7.6 pool acid,
either the liquid or the dry form should be added to the
water. Whenever any acid is introduced into the pool, it
should be diluted and thoroughly mixed throughout the pool, to
prevent corrosion. A high pH reduces the effectiveness of
chlorine as a germicide and an algaecide. This condition also
causes eye irritation.
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