Which minerals are primarily measured when assessing water hardness?

In assessing water hardness, the minerals that are primarily measured include calcium and magnesium. These two elements are the most significant contributors to water hardness because they are frequently dissolved in water, originating from soil and rock mineral sources. While iron and strontium can also be present in water systems, they do not significantly impact the overall hardness of water in the same way as calcium and magnesium do.

The presence of calcium and magnesium ions leads to what is known as "temporary" and "permanent" hardness in water. Temporary hardness is primarily caused by the presence of calcium bicarbonate, which can precipitate out upon heating. In contrast, permanent hardness arises from sulfates and chlorides of calcium and magnesium that do not change with heating.

Identifying water hardness is important in aquatic pest management, as it can influence the behavior, distribution, and survival of aquatic organisms, which are affected by the water's mineral content.