Just to clarify a couple of things.
Theoreticallly, the concentration of Seasalt (2 tsp per quart) is isotonic. It neither is absorbed or draws out water. So, it just goes through you. I always drink a couple of glasses of water an hour beforehand, just to be sure I am hydrated enough. I actually find it easier to get down a lot of saltwater than an equal amount of plain water. Anyway, even at that, I can still hold on to a lot of water.
As far as ES - the Liver-Flush dosage is 1 tablespoon in 6 oz. of water.
Or a quarter teaspoon just as a magnesium supplement.
2 tbsp of ES in a quart doesn't relate to anything I've seen.
There are other protocols on kidney cleanses.
Just as and FYI check out the Master Cleanse Forum and google it, too.