The cleansers like Easy Clean, One-Step, B-Brite and C-Brite will only keep for 4-5 hours. On the other hand, a sulfite solution will keep for 2-3 months in a sealed container.
Campden tablets are pre-measured amounts of sulfite, either potassium or sodium. I will have to get back with you on the amount to use as I am not in the store and I need to look at the bottle. The potassium and sodium are slightly different in the amount to be used. The sodium based is 8% stronger.