The clunk should NOT be able to swing forward in a standard tank

Minnflyer, I think you are on to something here and I wonder how many folks are hip to this. For example, the illustration you gave shows a stiff piece of tubing in the clunk line to keep it from going foreward in the tank and kinking. How many people (especially the ones who use std silicone tubing) actually do this??? It appears that we all should.

Okay, so the funky clunk tubing supplied by tank mfg's is actually LESS flexible than standard tubing..... and now we know why...

Thanks a whole bunch!

Ernie