Basic Swimming Pool Chemistry – Chemical Balance Explained
In addition to sanitisation, you also need to chemically balance your pool water.
The chemical balance of your pool is made up of:
pH (acidity/alkalinity level): 68%
Total Alkalinity (TA): 16%
Calcium hardness: 16%
Chlorine and pH levels should be monitored at least once a week or every day if your pool is in high use.
Total Alkalinity and Calcium hardness levels can be monitored less frequently.
Maintaining the pH level of your pool is critical to providing a safe environment for swimmers.
Incorrect pH levels can cause itchy skin and red eyes. It can also reduce the effectiveness of chlorine.
PH ranges from 0-14, with 7.0 being neutral, above 7.0 alkaline, and anything below 7.0 acidic.
The Australian Standard for swimming pool water is 7.0 to 7.8, with 7.4 being ideal.
Rain, water top-ups, swimmers and chlorine will all alter your pool’s pH.
PH levels can be raised by adding soda ash (which is alkaline) or lowered by adding acid.
Total Alkalinity (TA)
Total Alkalinity is the measure of bi-carbonates, carbonates and hydroxides in your pool water.
Low levels will cause erosion to pool surfaces and corrosion of equipment.
It can also cause pH levels to become very unstable.
The Australian standard recommends that your TA level should be 60 to 200 parts per million.
You can raise the TA level by adding ‘buffer’ – sodium bicarbonate – or lower it by adding acid.
Bear in mind, adding acid will also affect your pH levels.
Low levels of dissolved calcium in pool water can corrode pool equipment and high levels can create scale.
Calcium hardness levels can’t be monitored using most domestic pool water testing kits.
In areas where calcium levels aren’t high, you shouldn’t need to do this test more than once a year;
unless you use calcium hypochlorite to sanitise your pool.