What is the effect of high calcium hardness in pool water?

High calcium hardness in pool water primarily leads to scaling on pool surfaces and equipment. When the calcium levels are elevated, the water becomes oversaturated with calcium, which can precipitate out of the water and form deposits on various surfaces such as tiles, pool walls, and even within filtration systems. This scaling not only hampers the aesthetic appeal of the pool but can also impact the efficiency of pumps, heaters, and other equipment by obstructing water flow and potentially causing mechanical issues.

The other choices address potential concerns that are often associated with pool chemistry, but scaling is the most direct and prominent issue arising from high calcium hardness. Water clarity can be affected, but this is more typically related to issues such as pH balance, turbidity, or inadequate filtration rather than directly related to calcium hardness alone. While corrosion is more commonly a result of low calcium hardness or low pH, high calcium hardness typically does not lead to increased corrosion risk. Similarly, high calcium hardness does not inherently raise chlorine demand, as that is influenced more by factors like organic material in the water or water temperature.