Well I have the 501. secured a couple "L" braces for it to stand on under my desk and now I'm just waiting for the silicone to dry where the airline and the 1/4'' 501 tubing come together.
I didn't find barbed reduction fittings for the two lines with out doing some indepth searching and I figured any barbed fitting that'd go into an air line would reduce the flow capacity even more so with such a narrow opening. So I slid the air line about an inch n' a half down the 501 line and put about an inch of silicone in the junction. Should work like a champ. Not the prettiest but it'll be under the desk. Pictures coming when it's all dry and opperational.
I feel the bug coming over me with planted tanks now! Uhh Ohh...