The concentration of magnesium salts in a system is usually considerably lower than that of the calcium. In addition, magnesium salts are usually more soluble than those of calcium, with the result that calcium will precipitate first. This combination of factors results in reduced scaling potential.

Normally found in well water, the behavior of manganese is similar to that of iron but more difficult to control. Manganese can exist in either the +2 or +4 oxidation states and forms a tenacious, black deposit in cooling water systems. Manganese deposition is usually controlled through the use of sequestrants such as HEDP phosphonate or polymeric dispersants.