I use Epsom salt and Soapsuds, together in the SAME usually 3 QT enema for the FIRST ROUND of an enema session, and soapsuds only after that.
Epsom Salt has a strong purging effect. so it is highly effective, but that does NOT mean "more is better"
One disadvantage to it is that it has a rather narrow "Therapeutic Window" that is the difference between the best purge you can get out of it and a dangerous overdose is not much at all. I would advise a first-time user to go easy at first. 2-qt bag, no more than 4 teaspoons. Less if you are on the small side.
I manage to retain it 15 minutes almost every time, but I've been at it since pre-teens Now in my late 20s
When you want a strong purge, go ahead and try Epsom salt and soapsuds, but heavy on the soapsuds, light on the Epsom salt at first. Knee chest position, at least through the first 3 or 4 sessions so that gravity actually works WITH yo instead of against you in retention.
First round ONLY and finish the job with soapsuds.
Empty stomach!! At least 8 and better 12+ hours without solid food or alcohol, and at least 6 hours without caffeine. Even then keep an empty dishpan or trashcan within arm's reach of the toilet, just in case it still decides to come out both ends at once.
Take it easy for the next 12-18 hours as far as what you eat and how much. Too spicy or irritating can cause problems.
other than that, the rules are no different than for any other cleansing enema.
Take as much of the bag as you can.
Retain it 15 minutes if physically possible. if not, as long as physically possible
Once in position, stay in position through injection and retention. Keeping an old worn out washcloth or hand towel in arms reach that you can use as a bite rag or a twist rag can help a lot
Take your time. don't do this if in a hurry. Cell phone OFF Laptop or tablet OFF. other residents including pets taken care of and OK for a few hours.
Once you insert the nozzle, make SURE you have it pointed towards your navel, and are as relaxed as you can be in the knee-chest position
make sure it is not knee-neck helps to have a pillow under the knees and another under the chest so the weight is NOT on you head or neck, the head rests on the bed itself.
If you are an XX or a TG, the pillow under the knees should be slightly higher. A regular non-underwire bra is OK, NOTHING that interferes with your breathing, NO wonderbras longlines etc. Take off any Spanx before you get into position.
Take a couple of minutes and relax. Two or three deep breaths before opening the valve is a good idea.
Take it easy for the first 3-4 hours after you think the last round of the enema is out. You WILL get another expulsion of several ounces in that time.