Which minerals are primarily measured when assessing water hardness?

Water hardness is primarily assessed by measuring the concentration of calcium and magnesium ions present in the water. These two minerals are the main contributors to water hardness, as they can form insoluble precipitates with soap and affect the behavior of certain aquatic organisms. While strontium can also contribute to hardness in smaller amounts, calcium and magnesium are the predominant indicators used in hardness measurements.

By focusing on these minerals, water hardness can directly influence various aquatic processes, including the growth and health of aquatic life, the efficacy of chemical treatments, and the maintenance of equipment in water systems. Other minerals listed in the alternative choices do not play a significant role in determining water hardness, which helps clarify why they are not considered primary indicators.