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Total Alkalinity. The total alkalinity (TA) is a measure of how much of the alkaline substances there are in the water. In the swimming pool water, we are concerned with bicarbonate alkalinity, which should be between 80 ppm and 120 ppm.When the total alkalinity (TA) is within this range, it prevents rapid pH changes and stabilises the pH level.ote that you should only add sodium bicarbonate at the rate of 1 kg per 50,000 litres of water every 4 days. Raising the TA can therefore be quite a time-consuming, slow process. Lowering the total alkalinity is also a slow process.
It is recommended that the results of total alkalinity be considered before adjusting pH. The direction of pH change, or even the need for adding chemicals, is greatly influenced by the level of total alkalinity. Total alkalinity does not vary quickly and often is only tested once a week.Calcium Hardness Levels. Tests for calcium hardness are performed at the beginning of the swim season, when you start up a new pool or after draining and refilling a pool or spa. After that, they only need to be done every three months or so.otal alkalinity does not vary quickly and often is only tested once a week. Calcium Hardness Levels. Tests for calcium hardness are performed at the beginning of the swim season, when you start up a new pool or after draining and refilling a pool or spa. After that, they only need to be done every three months or so.