This is information I got from my naturopath a couple of years ago. It is best to do a flushing enema before a retention enema. Salt, vinegar and lemon juice all help clean out the lower portion of the colon better than just plain water (note-I have tried them all, I got the best results with white vinegar, the lemon juice burned). After you are sure all the fluid from the flushing enema is expelled, then you can do the retention enema. Generally much less fluid is used when doing the retention enema. For a coffee enema use about two cups, this will allow the solution to flow into the intra hepatic veins. For a probiotic infusion enema 1-1 1/2 cups a liquid is used and the abdomin should be massaged while the hips are raised to allow fluid to gradually reach deeper areas. These are the only two retention enemas I've ever done. I'm sure Shelley can give more exact information.