Feed Rate
 

In water treatment feed rates are established for fluoridation, chlorination, and coagulation chemicals to name a few.  It is common practice to express the amount of chemicals being added to water as parts per million, PPM.  Parts per million is equivalent to milligrams per liter.  The term part refers to a unit of weight and one part per million of a pound of substance would be one pound of said substance in one million pounds of water.  Feed rates are calculated based on need and a substance can be either fed by hand or by automatic feeders for both liquid and dry substances.