Plantagenet: I use a 3-qt HWB style bag. closed top.
For the soap, I put a bar of Ivory Soap in a 1-gallon sealable jug, at least a day before. and shake it up good, I set it aside and let it steep, then shake it up again a few hours later, and again right before I start mixing the enema.
I actually keep a couple of those in the closet at all times.
If there are any other laxatives involved I time them accordingly.
I then measure out the Epsom Salt. Get on the scale. A teaspoon for every 20 pounds that I HONESTLY weigh.
I shake the soapsuds up one last time, and pour HALF A BAG into the enema bag. I then add the Epsom Salt. and I let the tap run until fully hot. I fill the rest of the bag with hot water and attach the hose. Then I carry the bag into the bedroom by the hanger end,Set it aside and proceed with my setup and prep. That way, temperature will equalize across the whole bag, Epsom Salt will dissolve and propagate through the mix,and the soapsuds will spread into all the water as well.
Then, after I have peed, and am ready to get into position, I hang the enema bag so that it will be about 3 ft above my rectum when I'm in position. That should produce a flow of about a quart per minute. I retain that 15 minutes!! NO LONGER!! It can cause too much of the Epsom Salt to be absorbed into the blood stream, which is dangerous!
The expulsion:Typically on running to the toilet, I will get one large watery movement expulsion immediately. Then over the next 20 minutes or so, a number of large watery expulsions with ever smaller solids. The worst time is right after the first expulsion. If you had anything in your stomach, have an empty trashcan or dishpan standing by because you might lose it!!