Cooling towers concentrate minerals through evaporation, creating three distinct water-quality problems that a treatment program has to manage together: scale, biological growth, and corrosion.
Scale Control
As cooling water evaporates, dissolved hardness minerals concentrate and can precipitate as scale on heat-transfer surfaces, reducing efficiency and eventually damaging equipment. Antiscalants and SHMP are commonly dosed to keep hardness minerals in solution — see our guide on water hardness for the underlying chemistry.
See Antiscalant and Sodium Hexametaphosphate (SHMP) Technical.
Biological Control
The warm, wet, aerated environment inside a cooling tower is ideal for microbial and algal growth, which can foul heat-transfer surfaces and, in the case of certain bacteria, create a genuine health hazard. Chlorine-based disinfection — liquid chlorine, sodium hypochlorite or bleaching powder — is the most common biocide approach, typically dosed on a controlled schedule rather than continuously.
See Sodium Hypochlorite.
Corrosion and Blowdown Management
Corrosion inhibitors protect metal surfaces in the system, and controlled blowdown (deliberately discharging and replacing a portion of the concentrated water) keeps dissolved solids from concentrating indefinitely. Blowdown water typically needs to meet discharge norms before release — see our guide on ETP chemicals.