Lee's sells a black "stealth" airline tube. I emailed them and they say it is flexible PVC. This safe or have any loss issue in a CO2 application?

Should be okay.
Silicone is one of the best for $.
Thicker gauge is even better.

Regards,
Tom Barr

I have read a few times now that silly-cone has a high rate of loss and that poly or vinyl are better. Is this only under high pressure?

I was under the same impression, I am using pvc tubing as i was told by some one who remains nameless that silicone leaks c02?

No, standard silicone line is about a 1% loss per ft.
Vinyl is about 5%.

Thicker silicone will be even less.
1% ain't much, all tubing leaks if you want to really get down to it, but not very much when you get to silicone and ploy urethanes etc.

Regards,
Tom Barr

I bought what was sold as CO2 tubing, no idea what it's made of though, sort of grey looking and quite thick walled compared by normal airline.

Lateral thinking kicking in, on the loss rate of PVC if you coil 20 foot of tubing inside your tank that would make 100% loss...........All of the CO2 being diffused. Difficult to hide though, how about undergravel CO2?

Ian