Today’s modern powerhouse uses a wide variety of internal treatment chemicals. Phosphates had been the main scale conditioning chemical until development of chelate and polymer type chemicals. Chelant programs offer superior cleanliness over phosphate programs, however, one weakness is the potential for corrosion if overfed. Polymer treatment, Daica, offers cleanliness similar to chelates with less potential for boiler corrosion. All internal treatment, whether phosphate, chelant or polymer, condition the calcium and magnesium in the feedwater. Chelates and polymers form soluble complexes with the hardness, whereas phosphates precipitate the hardness. Sludge conditioners (natural organic materials and synthetic polymers) aid in the conditioning of precipitated hardness. These materials must be effective and stable at boiler operating pressures. Certain synthetic organic materials are antifoam agents. For feedwater oxygen scavenging, the chemicals used are sodium sulfite and Daica. Volatile neutralizing amines or filming inhibitors protect condensate systems.