What primarily causes water hardness?

Water hardness is primarily caused by the presence of dissolved metals, specifically calcium and magnesium ions. These minerals typically dissolve in water as it flows over rocks and soil, especially in areas with limestone and gypsum, which naturally contain high concentrations of these ions.

Hard water is characterized by higher mineral content, which can lead to various practical issues such as scaling in plumbing, difficulty in soap lathering, and potential impacts on aquatic life. In the context of applying aquatic herbicides, understanding water hardness is essential, as it can influence the effectiveness of certain chemicals and their interactions with the aquatic ecosystem.

While organic matter, high water temperatures, and excessive algal growth can all affect water quality and aquatic environments in various ways, they do not directly contribute to the hardness of water in the same manner as dissolved metals. Organic materials and algae can affect nutrient levels and clarity, while temperature changes can influence biological processes but are not the root cause of water hardness.