Chemistry and General Operations
CHLORINE, ITS PURPOSE AND APPLICATION:
Disinfection is the most important
single factor in maintaining a pool which is safe and healthful. Chlorine is the
most widely applied disinfecting agent for swimming pool water.
common form of chlorine for home swimming pool consumption is calcium
hypochlorite containing 70% available chlorine. This solid, white material is
available as either a free flowing powder, or tablets. Both types have excellent
stability under all normal storage conditions. In use, this material dissolves
quickly, releasing free available chlorine which is needed to kill bacteria.
Pool water should always contain 0.3 to 0.6 parts per million(ppm) chlorine.
This chlorine residual may be achieved by adding one ounce of granular calcium
hypochlorite for each 5,000 gallons of pool water. In order to be sure that the
pool water contains the proper amount of chlorine it is necessary to test
periodically using an ortho tolidine test set which is available at your dealer.
There are a number of factors which affect the rate at which chlorine is
consumed in the swimming pool. Chlorine dissipates more rapidly in warm water
than in cold water. Ultra violet light (sunlight) causes an increase in the rate
of consumption as does the presence of organic matter such as perspiration and
bacteria that are carried in on bather’s skin also increase the amount of
chlorine needed to maintain an adequate chlorine residual. For these reasons, it
will be necessary to add more chlorine on sunny hot days and when there are more
people in the pool than when the opposite is true.
should be added to the water by means of a chemical feeder or a dispensing
basket. If tablets are used, it is important to remember that they may bleach a
spot on the floor of the pool if they are permitted to rest there and caution
should be taken to make sure that they are beyond the reach of children who may
place them in their mouths. NEVER MIX CHLORINE WITH ANY OTHER CHEMICALS and be
careful to use a clean dry measuring device when handling this material since
any contamination may result in a chemical reaction which may cause fire.
Chlorine should be added to the pool approximately 15 minutes prior to
swimming. Tests for the presence of a chlorine residual should be made
frequently and additions of chlorine made as needed so long as there are
swimmers in the pool.
ALGAE… ITS APPEARANCE, CAUSE and DESTRUCTION
Algae are very tiny plants that grow in untreated water. The air contains
millions of algae spores which either settle into the water or are carried in
during rain storms. Once present in water they may be recognized initially, by
the formation of slime on the sides and floor of the pool developing into a
general cloudiness in the body of the water accompanied by a sudden increase in
the pH. In the advanced stages of growth, they take on a green color and, if
allowed to progress further, will take on a brownish color and emit obnoxious
fish type odors. Intense sunlight is very conducive to algae growth by causing
increased water temperatures and more rapid loss of residual chlorine.
can be said, as a general statement, that algae growths will not develop where
the proper chlorine residual is maintained at all times. However, it is most
difficult to maintain the proper chlorine residual at all times since intense
sunlight and increased water temperatures increase the consumption of chlorine
therefore making it more expensive to control the growth of algae. Should algae
be allowed to gain a foothold in the pool, "shock" treatment is often necessary
to remove the growth. This consists of applying from five to ten times the usual
amount of chlorine, when the pool is not in use. Allow the chlorine residual to
settle back to normal before resumption of swimming.
While chlorine may
be considered an effective algaecide, it should be apparent from previous
discussion on this subject that in order to be effective, it must be present.
Since the conditions under which algae grow most rapidly are precisely the same
as those under which it is most difficult to maintain an adequate chlorine
residual, it has become common practice to employ algaecides to control the
growth of algae leaving the chlorine free to act on bacteria.
factor in favor of algaecides is that most algae require much higher
concentrations of available chlorine than do bacteria for the same degree to
kill. There are many types of algaecides in common use the most popular of which
are the quaternary ammonium compounds and copper based products. Most quaternary
ammonium compounds are in liquid form and, since they tend to decompose rapidly,
frequent additions are required in order to maintain the proper active residual.
On the other hand, copper based products are predominantly granular inform and
require only a single application in a given volume of water with occasional
additions to compensate for dilution due to addition of new water.
ITS IMPORTANCE AND CONTROL
Just as an inch is a measure of distance, so
pH is a measure of acidity or alkalinity. We know that lemon juice is acid and
that lye is alkaline, but to help us express numerically just how acid or how
alkaline, we use the pH scale.
The pH scale runs from 0 to 14. A pH
reading between 0 and 7 is on the acid side. A pH of 7 is neutral, and pH
readings between 7 and 14 are alkaline. The pH of swimming pool water should be
controlled within the range of 7.2 to 7.8.
Water that is decidedly acidic
or alkaline is uncomfortable to the bathers. Irritation to eyes and mucous
membranes, vague skin discomfort, and bleaching of hair and swim suits is
usually caused by improper pH. Human beings feel comfortable in a relatively
narrow pH zone (7.2 to 7.8) and it is fortunate that the effectiveness of
chlorine is greatest in this same range.
Pool water which is acidic (pH
below 7) is corrosive to filters, pipes and other metal fixtures and will result
in excessive chlorine consumption. Overly alkaline water (pH above7) tends to
form unsightly whitish deposits called "scale" which adhere to pool fixtures. In
this alkaline range, the effectiveness of chlorine is greatly reduced.
CONTROL OF pH
Adjusting the pH of water is a simple matter. To raise a pH
which is below 7.2, soda ash or pH positive powder or briquettes must be added.
To reduce a pH which is above 7.8, muriatic acid or pH negative powder must be
Swimming pool water is considered hard when it
contains dissolved solids in amounts which are objectionable to bathers,
equipment, or appearance. Calcium, magnesium, iron and manganese are the
chemicals which are the chemicals which are of primary concern. These minerals
enter the pool in the water supply, and may also be picked up from piping and
pool accessories used in the pool system.
The presence of calcium and
magnesium contribute to white cloudy water while iron and manganese usually
cause colored water.
Most hard water conditions can be alleviated through
the addition of water softening agents. Cloudy water conditions caused by
calcium and magnesium are usually the result of too high a pH and may be easily
corrected by adjusting the pH to between 7.2 and 7.8.
Well water or
ground waters usually contain high percentages of iron and manganese. Pool
waters which contain these minerals may not initially appear to have any color,
but upon addition of chlorine, they may be oxidized and will appear as a yellow
to brownish color. Colored waters may be eliminated by the addition of water
softening agents or by the proper use of alum.
FOR--Bermuda Dunes, Cathedral City, Coachella, Indian Wells, Indio, La Quinta,
Palm Desert, Palm Springs, Rancho Mirage, Thousand Palms,