Scale formation — evaporation in the cooling tower concentrates dissolved minerals (Ca, Mg carbonate/sulphate) in the recirculating water, which precipitate on heat-exchange surfaces as scale, reducing heat-transfer efficiency.
Corrosion — dissolved oxygen, low pH, chlorides and microbiologically-influenced corrosion attack piping, tower fill and heat-exchanger metal, shortening equipment life and risking leaks.
Biological fouling (biofilm/algae growth, and specifically Legionella risk) — the warm, wet, aerated environment of a cooling tower is an ideal habitat for microbial growth, which fouls surfaces, reduces efficiency, and creates a public-health hazard if aerosolized.
All three are managed together through a cooling-water treatment program: blowdown/cycles-of-concentration control to limit scale-forming mineral buildup, corrosion inhibitors and pH control, and a biocide/anti-fouling program.
