2. On the bottom (the weight side), you will want to drill one or two small holes, just a HINT larger than the air holes. This allows the water to escape from the bottom when the pressure comes on after being off a while. That way you don't end up with a nasty water pool in the bottom.
I second Bill Cody's advice about suspending the bubbler off of the bottom, especially if air is being directed out that direction. Having it lay on the bottom might stir up a lot of stuff and cause visibility/turbidity issues.
