pH is a measure of the acidity or alkalinity with 7pH representing the neutral point where water is neither acidic or alkaline.
Pool and Spa water should be maintained above 7pH and below 7.6pH with the ideal range somewhere between 7.2pH and 7.4pH. Getting the pH right is the first thing you should do and saves money in chemical use and equipment maintenance.
If the pH value is too high (above 7.6pH) then the free chlorine in your pool is less effective. Bacteria and viruses which would have been killed off by the free chlorine remain in the water and can cause infections, some of which can be severe. Too high a pH can also result in green algae growth as the free chlorine is made ineffective.
Too low a pH value can lead to corrosion of all the metal parts in your pool or plant room such as ladders, heating elements, lighting and so on. In addition, when the pH is below 7pH ‘bound’ chlorine can cause irritation to the eyes.
An important point to remember is to always measure the pH value of your pool or spa water when it is at the temperature you wish to use it. This is because pH will increase as the temperature of the water increases. If a water sample is taken from you pool and allowed to cool before you take the pH reading, then the pH reading you obtain will not represent the true pH value of the water in the pool or spa which is at a higher temperature.
Because the pH value of the water in your pool or spa is so important to get right we recommend using an electronic digital pH meter rather than test strips or phenol red tablets to measure pH. Not only do digital pH meters provide an accurate pH reading without having to interpret a colour change, they are also not susceptible to the colour being bleached out by too much Chlorine, something that can happen with colour comparison methods such as phenol red or test strips.