Astralpool 46888A Manuel D'installation page 4

Why pH is important?
"THE IDEAL PH VALUE IN A POOL SHOULD BE BETWEEN 7.2 AND 7.6".
As previously stated, sufficient residual chlorine must exist in the pool to destroy unwanted micro-
organisms, in fact the chlorine will only act as a bactericide when the pool water has a pH of between
7.2 and 7.6.
There are other reasons which call for a correct pH level: Once above 7.6, calcium in the pool will pre-
cipitate to a visible cloudy form (accentuated in hard water areas).
This gives a milky appearance to the water, and hinders the filtering, deposits may also appear on the
pool walls and fittings.
Once the pH level falls below 7.0 the pool water becomes corrosive causing eye irritation and affecting
mucous membranes. There is also a long term threat to metallic parts in the pool.
The quality of the pool water is highly dependent on maintaining the correct pH level.
CHLORINE
Standards for the amount of residual (free) chlorine in the pool water may vary from country to country,
depending on health authority regulations. Typical legal requirements are between 0.2 and 0.6 parts per
million, (i.e. 0.2-0.6 milligrams per litre).
What is understood by free or residual chlorine?
Even after the filtering process, certain bacteria remains to be destroyed by the disinfecting action of
the chlorine which is usually acting on the bacteria in the form of hyperchloric acid.
A quantity of chlorine that is added to the water (in excess of that needed to destroy bacteria and oxi-
dize organic material) remains free to combat new bacteria introduced by bathers or atmospheric
agents.
This chlorine remaining in the water in the form of hyperchloric acid is known as free, residual chlorine.
FILTRATION
It is essential that the filtration is accompanied by chemical treatment of the pool water.
The two processes are complimentary to each other.
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