The oxidation/reduction ...
Published by Joseph Cotruvo, President at Joseph Cotruvo & Associates, Water , Environment and Public Health
The oxidation/reduction chemistry of chlorine and SO2 or bisulfite is fast and complete. The only reason that bisulfite or sulfur dioxide would not be sufficient is that the treated solution is not well mixed and/or you did not add enough to meet or slightly exceed the stoichiometry requirement. Forget the GAC.