I personally believe that a daily enema is essential during a fast, and a saline solution is the most mild and appropriate in this circumstance. A quart and a half of solution at just above body temperature is perfect. You can even use regular table salt . One teaspoon per pint, or 4 teaspoons for a full bag.
Once into the routine, many people fasting say they actually look forward to their daily enema, as it provides relief and a feeling of well being.