There is a long list of impurities to be found in water entering a boiler. However, in the drycleaning and laundry industries, the major impurities affecting the operation of boilers are dissolved solids (known as TDS, or total solids) and oxygen which is dissolved in the city water entering the return tank. This oxygen combines with carbon dioxide to form carbonic acid, a destroyer of the metal in the boiler and piping throughout the steam/return systems. The concentration of acids in boiler water is indicated by the Ph (Ph-is a scale used to specify how acidic or basic [or alkaline] a water-based solution is). TDS and Ph levels indicate the condition of the treated water entering as well as inside the boiler, allowing us to adjust the blow-down frequency as well as the volume and timing of boiler compound addition to the return tank to prevent boiler damage.