In your pool it will manifest itself in the form
of slime on the sides and floor of
the pool, and a general cloudiness
in the body of the water accompanied by a sudden increase
in the pH. In an advanced stage of growth, it will
take on a green color and if allowed to progress
further, a brownish color with an obnoxious
fish type odor. Intense sunlight is very conducive
to algae growth due to higher than normal water temperatures
and an increased rapid loss of residual chlorine.
As a rule of thumb, algae
growth will not develop where a proper chlorine
residual is maintained. However, it is
most difficult to maintain a proper chlorine residual
in situations when intense sunlight and higher
water temperatures increase the consumption of chlorine.
Therefore, making it more expensive to control
the growth of algae. When algae build up gains an
advantage on your pool, a "shock" treatment(s)
is often necessary to remove the growth. This consists
of applying from five to ten times the normal amount
of chlorine, when the pool is not in use. Allow the
chlorine residual to settle back to normal before
resumption of swimming.
Another factor in favor of algaecides, is that they
require much higher concentrations of available chlorine
do bacteria in order to kill them.
There are many types of algaecides, the
most popular of which are the quaternary ammonium
compounds and copper based products. Most quaternary
ammonium compounds are in liquid form. Since
they tend to decompose rapidly, frequent additions
required in order to maintain the proper active residual.
On the other hand, copper based products are predominantly
in a granular form and require only a single application
of a proper dosage with occasional additions
to compensate for dilution due to addition of new
While chlorine may be considered an effective algaecide,
in order for it to be effective, its presence must
be felt. Conditions under which algae grows most rapidly
is precisely the same when it is most difficult to
maintain an adequate chlorine residual. Therefore,
it has become common practice to employ algaecides
to control the growth of algae leaving the chlorine
free to act on bacteria.