Campden Tablets SMS (Sodium Metabisulfite) prevents wild yeast, bacteria growth, and oxidation in your wine. Sodium Metabisulfite also works well as a sanitizer for your wine making equipment. The convenient tablet form takes the guesswork out of measuring. Each tablet adds 75 ppm free SO2 per gallon (pH dependent). Grind the tablet into a powder and dissolve in water before using.