Which substance is NOT used to increase Calcium Hardness?

The correct response indicates that magnesium hydroxide is not used to increase calcium hardness in pool water. Calcium hardness refers to the concentration of calcium ions within the pool water, which is crucial for preventing issues such as corrosion of pool equipment and plaster damage.

Magnesium hydroxide, while it may serve other purposes, does not contribute to the calcium levels in water. Instead, it primarily serves as a pH stabilizer or clarifier. Conversely, substances like calcium chloride, calcium sulfate, and calcium bicarbonate are directly associated with raising calcium hardness.

Calcium chloride is often used for quick adjustments in calcium levels due to its high solubility. Calcium sulfate can also be added to increase calcium levels, although it disassociates more slowly compared to calcium chloride. Calcium bicarbonate serves a similar purpose by dissolving in water to release calcium ions, thus enhancing calcium hardness as well. Understanding these differences is essential for proper pool maintenance and ensuring the water chemistry remains balanced.