While there are many factors that influence the formation of scale in cooling water systems, the three major factors are; temperature, pH, and water composition. Many scales found in cooling water systems have inverse solubilities with respect to temperature and pH. Specifically, as the temperature and pH of the water increase, the solubility of many scales decreases, resulting in a increased tendency for system deposition. Accordingly, the water composition is an extremely important variable in determining the scaling potential of a water. In general, the higher the concentration of scale forming Ions, the greater the potential for scale formation. The following is a brief discussion on various scales encountered in cooling water systems.