Sodium Metabisulfite in tablet form. General usage is one tablet per 1 US gallon (provides approximately 65 ppm of sulfur dioxide/SO2). Similar usage to Potassium Metabisulfite but Sodium Metabisulfite releases sulfur dioxide (SO2) at a higher rate and adds dietary sodium.
Usage: 1 crushed tablet per gallon
Sometimes referred to as "SMB" or "SMS"