This mod uses about 2 feet of regular air line, a small piece of rigid tubing that fits just
inside of the air line tubing and a simple airline valve (all should be available at any lfs), and some good glue - I used Weldon.
The rigid air line tubing - cut a piece about 3/4 of an inch long.
Cut a section of airline tubing about 2 " long, and another about 2 foot long
Drill a hole in the u-tube so the rigid tubing JUST fits in it (be sure to remove all burrs from the rigid tubing after you cut it). Glue it in place. You want it to extend only the smallest about inside the tube.
Let it dry thoroughly.
Attach the short piece of air line
Insert the air valve
Attach the remainder of air line tubing.
Open the valve to suck out the air bubble from the u-tube, close valve once it is gone.
I usually just coiled the airline on the top of the overflow box when not in use. (don't detatch it
)
...I also throw down a towel on the floor when I am working on the tank
I will copy & past from this post and make these instructions a thread on the DIY Forum also.