SWIMMING POOL WATER QUALITY

IN ORDER TO MAINTAIN ACCEPTABLE QUALITY THE FOLLOWING PARAMETERS SHOULD BE MAINTAINED:

· pH 7.2 - 7.6
· Free Chlorine 1.0 - 2.0 mg/l
· Combined Chlorine residual should be kept as low as 0.5 mg/l and should be no more than one-third of total chlorine.
· Total Alkalinity 80 - 150 mg/l
· Calcium Hardness 200 mg/l minimum
· Total Dissolved Solids (TDS) maximum 1000 mg/l above supply water TDS to an absolute maximum of 3000 mg/l (2000 mg/l preferable)
· Sulphate 360 mg/l maximum

WATER BALANCE IS AFFECTED BY TEMPERATURE, pH, TOTAL ALKALINITY, CALCIUM HARDNESS and TOTAL DISSOLVED SOLIDS. THE LANGELIER FORMULA, SOMETIMES CALLED THE SATURATION INDEX, IS USED TO DETERMINE POOL WATER BALANCE.

SATURATION INDEX (SI) = pH + Temperature Factor (TF) + Calcium Hardness Factor (CF) + Total Alkalinity Factor (AF) minus Total Dissolved Solids Factor (TDSF).

The value obtained should fall between 0 and 0.5 and indicates the water is in balance.

For further information contact ALAN SARGENT on 01483 444372.

Page updated January 20, 2003

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