Scale-inhibiting chemicals are available to retard or prevent all types of scale. They mostly function by enveloping a newly precipitated crystal, thereby retarding growth. Common scale inhibitors include

• Inorganic phosphates (inexpensive but only applicable at low temperature),

• Organic phosphate esters (easy to monitor but limited to temperatures below 100 F),

• Phosphates (easy to monitor and have a higher thermal stability to 150 F),

• Polymers (best thermal stability and effectiveness, but difficult to monitor).