The total quantity of calcium dissolved in the pool water is called calcium hardness. Calcium hardness
Calcium is important because high levels are unstable and become increasingly unstable if the pH or total alkalinity rises above normal levels.
These imbalances can result in water turbidity or scale build-up. In addition, calcium does not like hot water. As the water temperature rises calcium is more and more likely to precipitate. It is also very soluble in cold water, which is why scale deposits are often seen on heater equipment.
With all the difficulties that calcium can cause it would seem logical to use soft water to fill the pool. But this is not a solution to the problem! While high calcium levels can cause water turbidity and scale problems, soft or low calcium water is also a problem. This water is considered aggressive and can remove calcium from pool parts in order to meet the water's needs for the metal.
If the pool is made of vinyl or fiberglass, low calcium water can damage the metal components creating small holes and water leaking into the heater. If this type of corrosion occurs, stains may appear on the surfaces of the pool. It also destroys the vinyl or fiberglass surface that we may have.
The recommended amount of calcium is 100-400 ppm and depends on the water temperature. But unlike pH or total alkalinity, both of which can go up or down with relative ease, calcium levels cannot.
If we add a chemical that increases calcium hardness to the water then we can increase the calcium levels. Conversely, there is no easy way to reduce calcium hardness. The only way to reduce calcium hardness in pool water is through dilution with water of lower hardness. Over time calcium hardness naturally builds up in the pool due to evaporation and other factors, unless the pool water is regularly diluted.
So although it may be difficult to reduce calcium hardness, it is possible that we can control it so that we do not face the problem of water turbidity or scale deposits. The best way to minimize the effect of high calcium hardness levels is by using an isolation agent.
A sequestering agent is a chemical compound that when added to water binds with calcium and other minerals and makes them soluble. This means that calcium will still be present in the water, but in a form that is less likely to cloud the water or cause scale build-up if the pH or other factors get out of balance. In addition, since the calcium will still be in the water, there won't be the corrosion problems that we would have if the water were soft. An additional advantage is that high calcium levels can be tolerated without the constant need for dilution.
This is especially important when the pool is located in hard water areas or calcium based chlorine is used. The isolation agent should be part of the regular pool maintenance program.
When facing calcium hardness problems in the pool, the best solution is to contact the pool specialist. He can recommend products that are best for the pool and make sure they prevent any problems that arise.