> Campden tablets are premeasured amounts and can be made with either
> sodium or potassium, if used crush first. *I prefer potassium
> metabisilfite (K2SO4) as it is easier to use and cheaper. *5 campden
> tablets = roughly 1/4 teaspoon K2SO4 *as I recall which works out to
> 40 to 50 PPM free sulfite addition in 5 gallons (US) of wine.

K2SO5, apologies. I'm not a chemist...

Joe