Flow indicators are useful for enemas on the toilet, especially facing backward and watching the bag. I’ve learned over the years how to do an Ayurvedic / yogi technique which involves basically exhaling completely, then with little air in the lungs, sucking the gut up and under the rib cage. This creates some negative pressure in the colon and apparently experienced practitioners can even suck water up through a tube (they apparently used to do this in rivers), but I can’t manage nearly that level of suction, only enough to drain a bag that’s level with my chest. The pinwheel helps give visual feedback, and using an anti-back flow valve requires too much pressure to pop it open, so the pinwheel is a good training tool if you’re attempting to learn this technique.
I’ve used a few types of flow indicators over the years. The Bel-Art brand are overpriced labware articles and made of clear plastic that tends to crack, especially along the seam or on the back, causing leaks. The ball type is fun because it clicks with each revolution, but the fluid channels on that model are quite small and not suitable for any enema soliton which contains suspended particles that don’t dissolve, such as coffee enemas filtered in a French press, wheatgrass, damiana, aloe leaf extract powder, etc.
I’ve since acquired https://a.co/d/8a4hmoU which works well on larger tubing such as 5/16” and even. 3/8”. It’s a little more rounded with less “sharp” barbs than the photo they’re re-using, which is the Bel-Art version. It’s one of the least restrictive.
https://a.co/d/0U2gy15 is another that I’ve used, which can be seen on a bag here: https://en.zity.biz/gallery/image/290895 and it doesn’t clog even with two scoops of wheatgrass for a strong natural chlorophyll solution: https://en.zity.biz/gallery/image/290869 The wheel in particular on this model is well-suited to handling more viscous fluids as it has a bit of clearance around the edge, which also means it doesn’t spin quite as fast as the Bel-Art.
https://en.zity.biz/gallery/image/290850 is the Bel-Art with the ball. The barbed ends on this are also not great (fragile and not very sharp / bad grip), so I ended up using zip-ties on it to keep it attached to tubing.
https://en.zity.biz/gallery/image/290560 is another Bel-Art model, also overpriced and TINY. As you can see, the pinwheel is only about the size of a dime. The barbs ramp very quickly on this, and it felt like it might damage the exit port on a bag, so I’d only recommend using this on tubing. It’s available on Amazon as well: https://a.co/d/7vZdNxO . I haven’t tried that one with wheatgrass to see how well it does, but honestly there are better options.