I have both kinds of bags... Closed sytem ... hot water bottle syringe and also several fountain "open top" syringes. But, my absolute favorite or all favorites is one that is clear. I made it using an old Frasenius 5 liter Solution bag that we used on our daughter while she was on Peritoneal dialysis years ago. I completed the homemade syringe by attaching a Fresenius drain tube to the bottom connector of the bag and attaching an old time metal shut-off and a black douche nozzle to the end. Then, to finish it off, I cut a slice at the side of the bag opposite the drain tube closest to the hanging hole so I can add my enema water.
As for me, I love to see the water drop in the bag as it flows into me and to aid my visual effects, I often add food coloring to the water, along with the soap and salt before pouring it into the bag.
I am getting somewhat forgetful now... Every now and then, though, I forget to add the hot, soapy, salty colored water to the bag before kneeling on the bathroom floor.
So, as a result, My lovely wife will tell me "Mike, you forgot your water, again, it won't do you any good remaining in that pitcher." You know, wifey is always right...