Your orginal question asked if Oxypowder was good for the day after cleanse, not in lieu of Epsom Salts during the flush. I DO use Epsom Salts , but limit the Epsom Salts to a weaker solution as part of the flush itself.
I have also done a Liver Flush using coffee enemas to dilate the bile ducts. You've indicated that you are an "exit only" kind of flusher so the coffee solution will probably not appeal.
If the problem you are experiencing with epsom salts relates more to dehydration, you may want to prepare for the flush by drinking electrolyte water (The company that makes Emergen-C also makes an electrolyte mix that you can mix with a quart of water)for a few days before and then during the flush, and reducing the amount of epsom salts in the flush solution. I release stones with only 1 teaspoon of epsom salts to a glass of water.
Any chance that you may be allergic to sulfur? Epsom salts are magnesium SULFate.