Spa hot tub chemical guide: Water balance

Water balance is important to the overall performance of your spa. Everyone’s spa water conditions vary. The water source, location of the spa and frequency of use all effect the water balance.

Unbalanced water can damage the equipment, make the water uncomfortable for the user, and decrease the effectiveness of the disinfectant. Total alkalinity, pH, and calcium hardness must be within the correct range to balance the water.


Simply, pH is a scale indicating whether spa water is basic, neutral or acidic. Spa water should be slightly basic 7.2 – 7.6

A low pH below 7.2 leads to corrosion of spa equipment and will irritate the skin of the bathers. The sanitiser will dissipate more rapidly. A low pH can be corrected by adding pH UP.

A high pH above 7.6 promotes scaling on heat exchange tubes, creates cloudy water, calcium deposits and reduces the effectiveness of disinfecting agents. A high pH can be corrected by adding pH DOWN.


Total alkalinity is a measure of the alkalines in the water. They act as a pH buffer or a pH stabilizer preventing large changes in the pH. The total alkalinity should be between 80–150 p.p.m.; ideally 120 p.p.m. Tablet chlorines and bromine tend to gradually lower the alkalinity level.

To raise the total alkalinity add ALKALINITY BOOSTER.

To lower the total alkalinity add pH DOWN.

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