I'm trying to pin this whole issue down a bit better. Using this web
site ( http://www.mcmaster.com/ ) I found that Eric's translucent, 50
Duro silicone tubing with 3/16" ID and a 5/16" OD is McMaster-Carr P/N
51135K23. It is $0.74 per foot for 10, 20, 50 and 100 foot lengths.

I think O-rings would work better than Bumper's caulking tube clamps,
because I think O-rings will have better quality control. McMaster-Carr
has a mind numbing selection, but specifying 70 Duro silicone rubber
O-rings with a 5/16" ID and a 3/32" width gives McMaster-Carr P/N
9396K74. They are $9.93 for a pack of 100.

What I'm not sure of is the optimal ID and wall thickness. I picked
5/16" OD so they would easily roll over the tubing above, and 3/32"
width because it would be slightly stronger than 1/16" while still not
much more expensive. However, a 1/4" OD with a 1/16" width would surely
hold tighter - but might it distort the tubing to the point of leaking?
I don't know - opinions?

-John