I’ve had a few colonics and lots of experience with >4 liter enemas. There are a few things to consider, one of which is that unless you have some sort of condition that would cause it, your digestive system doesn’t just stop even when undergoing one of these procedures. I’ve done juice fasts for about 24 hours before colonics and noticed better results from that, but you still get the bile you’d expect to be in your active system.
Enemas take multiple rounds to get to clear returns, which makes sense; it’s like trying to wash out a 5-foot-long piece of corrugated tubing with only water and expecting it to be squeaky clean after just a single rinse with no scrubbing.
Colonics have many fill and drain cycles, with different hydrotherapists approaching this differently. I’ve had a few which involved very long fill cycles until I reached their max safe pressure, and when I asked they said I had likely taken at least 6 liters before evacuating. It was definitely the largest volume I’ve ever taken. I’ve done a bit over 5 liters myself after lots of practice. During that session, I felt and observed the pressure increasing, then felt a small release internally and saw the pressure decrease a bit. The hydrotherapist postulated that this was due to the folds in the colon expanding and opening up, but I believe that some bit of solution was going up into the small bowel.
I wish I had more time with her, as that was a fantastic session and I felt extremely clean after. We also did a coffee enema implant through the colonic speculum, which I requested she push all the way up into me with again as much solution as I could take. She happily obliged me and although the coffee was noticeably more acidic and a bit harder to retain, I took again >5 liters by her estimation before an incredibly relieving expulsion cycle. The magical part of colonics compared to enemas in my opinion is the siphoning aspect of the closed system during the expulsion cycle. Due to there being very little or no air in the expulsion side, you get the same affect as a normal gravity enema, but in reverse: the expulsion cycle literally siphons the solution out of you. It’s a very unique feeling that I hadn’t experienced before, and it felt amazing. It also spares your bowels and anus the repeated cycles of pushing out a regular enema, so you get pretty much everything out in one cycle as opposed to trying to coerce your rectosigmoid junction to release, which is also easier when comfortably laying on a colonic table as compared to sitting on a toilet.
It definitely takes a lot less time to reach clear returns with a closed-system colonic vs any enemas I’ve ever done. I’m hoping that I can find a colon hydrotherapist willing to explore some of the limits with me and schedule me for a longer session to really see what is possible and experience the unique sensations. I have a much more detailed write-up of a couple of my colonic sessions that I wrote to someone in a private message that I should really post as a story here. For now, I’ll just say that although I’m obviously into the erotic aspects as well, all of my colon hydrotherapists have been very professional and I remained flaccid the entire time, though I did leak a prodigious amount of precum every session. I definitely got a bit into sub space during these and I’ve considered wearing a chastity cage to a colonic, but I don’t really want to cross that line of consent with someone who is a professional operating in a professional context and likely having no interest in participating in the erotic aspect with me in such an explicit way.