Calcium chloride is used to add both calcium and chloride ions to brewing water. Calcium is needed for proper mash and boil chemistry, and plays a role in many important chemical reactions in brewing. It is used at a rate of 50 to 150 ppm in brewing water. Chloride ions  bring out fullness and body in a beer, and are used at a rate of 0 to 250 ppm in brewing water. One gram per gallon adds around 70 ppm of calcium and around 125 ppm of chloride.