Can hydrogen peroxide be used effectively in place of sodium bisulfite for dechlorination of seawater RO feedwater? We are concerned about dissolved oxygen levels in the concentrate that is disposed back into the sea… What is the disadvantage of raw water disinfection by chlorine in RO desalination? Is sodium metabisulfite an effective disinfectant for my RO system? A few weeks ago, we pickled all RO membranes in our trains with sodium metabisulfite for long term storage. Our membrane manufacturer recommended that we change the solution once the pH drops below 3. We measured a decrease in pH for the first two weeks, but then on the third week, the pH increased. Can you explain why the pH increased instead of decreasing?