pH CONTROL AND ACID DELIVERY
'pH level' refers to a logarithmic scale from 0 to 14, where 0 represents the acidic end and
14 represents the alkaline end. A pH of 7 is neutral.
Generally a pH level between 7.2 – 7.6 is suitable for most pool types, however those
requiring a higher pH level will also require a higher chlorine residual.
Each pool finish and type has a specific range of pH that is suitable. You should seek
advice from your local pool professionals or your pool documentation to establish the
recommended pH for your pool.
Left unchecked, salt chlorination will over time increase the pH of your pool water to
around 8.4, and any addition of liquid chlorine can increase it further.
A high pH level will reduce the effectiveness of chlorine and can potentially cause scale on
the pool surfaces and equipment, and is irritating to the skin.
A low pH may cause the water to become corrosive, which can damage the pool surfaces
and equipment, and is also irritating to the skin.
The Pool Lab ASP will (by default) test the pH in your water three times per day, and will
automatically dose with dilute (16.5% maximum) Hydrochloric acid to maintain pH at the
desired value.
Total Alkalinity (T.A.)
The total alkalinity is a measurement of all the alkalis in your pool water. This includes
carbonates, bi-carbonates and hydroxides. It is measured in parts per million, or ppm.
These alkalis act as a “pH Buffer” which resist changes in the pH and help to keep the pH
level stable.
The most common and recommended way of raising the total alkalinity is by the addition of
sodium bi-carbonate (or bi-carbonate soda) to your pool water. Most pool shops will refer
to this as “pH Buffer”.
More advanced home test kits will include a test for total alkalinity, otherwise you will need
to have your water tested professionally to establish the correct dose to add.
The recommended T.A. for most pools is 80 – 120 ppm, depending on the interior finish.
Consult your local pool professionals or your pool documentation for the recommended
range for your pool.
Note: Reducing the total alkalinity is not as simple, and therefore over dosing should be
avoided. Consult your local pool professionals for advice on this if required.
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