No I don't have valves, because the diffusers that I used have a cfm rating of .5 to 5cfm and my pump only puts out a max of 7 so I didn't need to controll the air because I could have a max of 15cfm if I wanted it and I wasn't even close to that, but I suppose you could set it up that way if you had a diffuser in another area and wanted to push some air to that one as well, but I did not use any and it works great. The 4 circle things in the middle of my diffuser are 4 inch round wheel barings for weight. I needed them to weight it down enough to make it sink. The metal plate is from the side of a computer. I drilled holes in it in order to zip strip everyting down to the plate. And the wire you see is from hangers. I wrapped them together and then put a zip strip on the end of the wire and took some twine put it through the zip strip and lowered into the pond. Worked like a charm. Some guys use a tire to put there diffusers on that works good too.
