Molecular SO2 is the active form against microorganisms and unwanted bacteria. The recommended level of molecular SO2 for red wines is 0.5ppm (mg/L), for white wines is 0.8ppm (mg/L) and desert wines is up to 1.5ppm (mg/L) . You can use this table to determine how much Free SO2 is required to protect your wine, based on its pH. Free SO2 over 50ppm (mg/L) can be tasted and detect in nose of the wine.
|pH||Free SO2 needed for 0.5 ppm molecular SO2||Free SO2 needed for 0.8 ppm molecular SO2||Free SO2 needed for 1.5 ppm molecular SO2|