SOME TIPS ON WATER CHEMISTRY
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HOW TO ADJUST pH
A pH range of 7.2 – 7.6 is ideal for maximum comfort and chlorine efficacy. Always adjust
total alkalinity before adjusting pH.
Low pH (acidic water) leads to stinging eyes and corrosion of open metal fittings. Raise the pH
by adding sodium bicarbonate or soda ash. Consult your pool professional regarding which
chemical is best for your situation and the proper amount to use. Check the pH after 4 hours of
circulation, adjusting as necessary to achieve the proper range.
High pH (alkaline water) leads to clouding of the water and reduces the amount of active
chlorine. This means algae and bacteria can grow. Lower the pH by adding muriatic acid to the
pool water. The acid demand indicated by your 4-in-1 test kit will show the amount of acid to
use. WARNING:Always add acid to water, never water to acid.
If your pH remains inconsistent, check your total alkalinity.
TOTAL ALKALINITY AFFECTS pH
Total alkalinity is a measure of the alkaline chemicals in your pool water (e.g. bicarbonates,
carbonates, and hydroxides). It can be thought of as the buffering system necessary to control
pH. Low alkalinity can allow pH to fluctuate or drift rapidly in one direction. The pH will be
difficult to maintain and staining of pool surfaces may occur when total alkalinity is too low.
Total alkalinity should be in the range of 100 – 120 ppm. Total alkalinity is often confused with
pH. They are related, however distinct. To raise total alkalinity, add pH buffer (sodium
bicarbonate) at the rate shown in the manufacturer’s instructions to achieve a reading in the 100
– 120 ppm range. 180 g of sodium bicarbonate raises 10,000 litres of pool water by 10 ppm.
To lower the total alkalinity, use muriatic acid.The acid demand chart in your 4-in-1 test kit will
indicate the necessary amount to add. Adjust as needed until the reading (taken at least 24 hours
later) is in the 100 – 120 ppm range.When total alkalinity is correct, you may need to adjust pH.
WARNING:Always add acid to water, never water to acid.