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Mineral Deposits & Scaling
Mineral deposits left behind when water evaporates can impede your cooling system’s ability to transfer heat from water to air.

In any evaporative cooling system, scaling formation is an issue that must be addressed, regardless of the water source. Scale formation can increase energy consumption by reducing the heat transferring efficiency of any cooling system, and eventually may lead to system failure. Fortunately, with a proper treatment program, scaling from recycled water can be controlled to an acceptable level.

This table illustrates various scaling elements, the level at which they cause concern, and suggested control strategies.
  • All values in mg / l unless otherwise noted
  • This is operating range without treatment
  • Alkalinity measure of water's ability to neutralize acids

Water Quality Parameter(1)

Level of


(2010 avg)


Method of Control

(Ca, Mg)
1000-1500 >2000 266 mg/L as CaCO3 Contributes to scale depending on pH and anions
  • Lower pH (acidification)
  • Use scale inhibitors
Iron (Fe) 0.1 <0.1 107 ug/L May deactivate polymers used to inhibit calcium phosphate scaling
  • Consider KMnO4 to treat for iron in water.
4 <4 1.5 mg/L At calcium levels > 1000mg/l as CaCO3, PO4 can combine with the calcium to cause scaling.
  • Lower pH
  • Add polymers
  • Use calcium phosphate scale inhibitor
Silica (SiO2) 150 <150 23 mg/L Produces deposits
  • Pretreatment or sidestream filtration
Alkalinity N/A(3) N/A(3) 192 mg/L as CaCO3 Important means of predicting calcium carbonate scale potential.
  • Not applicable
Zinc >3.0 <3.0 2.32 mg/L Beneficial at low levels. Contributes to deposits at higher concentrations
  • Use scale inhibitors