Hey Shawn
So, yeah, I built the PVC pump. It didn't work right to start with because I used a bicycle inner tube for the inner tube bits. Then it didn't work right because my bottom disc wasn't sealing properly. Well... The second problem leads me to think that it might be easier or work better if the bottom disc was the diameter of the outside of the tube and just got glued on. Ok, ok, this removes some of the ability to field service the thing, but sheesh! How the heck do you make a disc the size of the ID of the pipe? Yeah - you wrote about maybe using a hole saw. But if I've gotta buy a hole saw, well, the whole venture is sure starting to get expensive!

But, if you went to the trouble of getting a hole saw, you -could- make two discs the size of the ID and then sand just a wee bit off of one of them. You could then outfit both of them as described for the bottom one (inner tube to 1/8" less than the diameter, a bunch of holes) and maybe use the sanded one as the disc on the plunger... (Still a small problem of sealing...) If it worked right, it would probably be a bit less effort to use as well as being a little more effecient.

(Not having asked ahead of time, I didn't put your link in the link box, but here it is for those who didn't already know it...
http://www.geocities.com/shawnkayak/pvcpump/)

cheers!
charles

ps: OT: I've just tried brewing my first maple ale... I could give a preliminary report when I go to bottle later in the week, but it had a pretty high initial sg so it shouldn't really be ready for months and months to come...