Ian;

When you say that Potassium Sulfite solution is alkaline, what you are really saying though is that there is an excess of OH- created when you add Potassium Sulfite to water. Again, the alkalinity comes from the equillibrium which causes OH- to break off from water and form an excess of hydroxide (or alkali) and thus, KOH is present in solutions of Potassium Sulfite.

PE