i’m preparing for my second time of wine making, and hoping for a sweet red wine (first batch was from an all inclusive kit that was drier than I like). My first question, in order to buy supplies, is: what is the difference between sodium bisulfite and potassium bisulfite? What do they do/how are they used? Which do I need, or both? And finally, are they harmful, as I read where some folks don’t like using them.