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Copyright © 2017 Watermaid Pty Ltd
Version 20170223
13
Pool Chemistry and General Information
13.1
Essentials for a Healthy Pool
There are three fundamental requirements for maintaining a swimming pool or spa:
a) Filtration
b) Chlorination
c) PH
A pool or spa should be looked at daily to check that the water is clean and clear and the finest details of the
walls can be seen at the deepest part. This will indicate whether the pool or spa has had enough filtration and
chlorination for the load conditions that were applicable the day before. Any other condition requires testing
and rectification before swimmers enter the water.
a) FILTRATION
It is first necessary to pass water through a filter to remove debris. A standard sized pool pump with normal
filter pressures will pump about 10,000 litres (2,642 U.S. gal) an hour, so an average 60,000 litre (15,850 U.S.
gal) pool
then requires six to ten hours of filtration a day in summer conditions. This will turn over the
equivalent of 1 - 1½ times the total volume of water.
However, about 65% only of the actual water and
debris will have passed through the filter.
For spas, the water usually turns over several times per hour.
Generally, at dawn and at dusk, any wind will die down, and are the best times to commence filtration. Leaves
and floating debris will be swept to the skimmer box without restriction if the pool is well designed.
Longer filtration cycles can reduce the chlorine requirement and conversely, more chlorine can reduce the
filtration requirement.
b) CHLORINATION
The WATERMAID® pool chlorinator takes care of the chlorination requirement.
As mild saline water flows
through the WATERMAID® cell, it is converted by electrolysis into chlorine
as sodium hypochlorite.
Chlorine
is required after filtration to react with any remaining debris (both visible and invisible), remove stains by
oxidation and sterilise the water of harmful bacteria.
A chlorine residual (or reserve) is required for any imminent bather load.
A total of 1 to 3 ppm for pools and 3
to 5 ppm for spas of free available chlorine is required to maintain a clean clear condition.