I see that my comment about physics has been shot down with a response that is backed my far superior education than mine. However, I will say, that the MICRO bubbles that I seen rise in the small tubes that I attached to my bleeders did allow the fluid and air to pass. I agree with what Brian has written, but I can also say that when I did this process, I was finally able to get my brakes to work. Mityvacs are nice, but I didnt have any results using mine. Good luck with your aggravation!