in order to get just a little K-meta in gallon recipes, what I do is wet the back of a sanitized spoon and place it in the powder, then mix that into the must. I know it's not precise measurements, but it seems to have worked for me so far. I've done about 60+ single batches that way. I don't like using campden tablets since they are mostly filler of some sort and require crushing, etc.
Oh, and the main difference between the sodium and potassium is that the sodium is a little more effective at killing bacteria. However, the use of Na-Meta has been limited due to a lot of people being on sodium reduced diets. It will not impart a salty taste in the quantities we will use. I've heard it that some smaller commercial wineries use Na-Meta to sanitize, and K-Meta for the wine.Edited by: Dean