Martin, roughly how much sulfate from one tablet would need to be accounted for in Bru'nwater (or other) ?
The packaging says one tablet/gal is "150 ppm", but not of what. So at one tablet per 20 gal, ~8 ppm of something or other. Probably SO
2 since that's what a vintner would actually be worried about.
My tablets mass ~650 mg. If you assume that's entirely K
2S
2O
5 - I'm sure there's also some sort of binder, but we'll establish an upper bound - that's 5.6 ppm of metabisufite, or 3.7 ppm of sulfate assuming my stoichiometry checks out.