Sodium or hydrogen zeolite ion exchange, lime softening and demineralization all remove Ions that cause scale formation, thereby eliminating the deposit potential for common hardness scales found in cooling water systems. However, with the exception of lime softening, these methods are usually cost prohibitive because of the large volumes of makeup water that must be treated. Therefore, the methods are typically used only in small systems, closed systems, or systems where temperatures are so elevated that high quality water is required to prevent deposition.

Cold lime softening is often used in plants operating on "zero blowdown" technology where no water can be discharged from the plant. In these applications, the cooling water cycles are very high because the only water loss from the cooling tower is that which is lost through evaporation and windage. Therefore, usually 3-5% of the recirculating water is softened so that scale-forming Ions can be kept at concentration within the limits of the chemical deposit control program.