... such as Ca 2+, Mg 2+, can soften hard water, change suspension into solution, slightly alkaline, without causticity. Usage Used as main ... %; 0.1 Iron, as Fe %; 0.015 pH of 1% water solution 9.2-10.0 2. Food grade Main content, %: 94 ... %; 0.05 Iron, as Fe %; 0.01 pH of 1% water solution 9.5-10.0 Heavy metal, as Pb %; 0.001 ...