I know this has been discussed to death and I'm not trying to rehash all of it over again. I honestly believe if you have a system that works for you, then you should stick with it. I've always preferred to use one type of tubing from my reg to my bubble counter at the tank, and a more pliable type from my counter to the diffuser. Strictly my own preference.
Just recently, I decided to pose the question to one of the leading manufacturers that I often deal with at work. My concerns were permeability, as well as "brittleness" with prolonged use. I use two of their other products currently and asked how they stack up.
----- I'm posting this with their brand names removed, as to strictly convey what their technicians responded with. I'm not trying to push a specific product. I just happened to find their response interesting, informative, and worded in a way that was easy to understand. -----
"Thank you for your interest in our products.
Please find answer below from our technical team -
OK - for general, low pressure use in conveying C02, the (tubing A) and the (tubing B) are good economical choices. It will become somewhat brittle over time, and there is a level of permeability to most gases due to the plasticizer used in both, inherent in most flexible materials.
The best choice would be (their version of "beverage" tubing), not only is it a polyelfin liner, but since it is cross-linked, there is far less movement of the polymer chains as they are "linked" together. Of course, (bev. tubing) is not nearly as economical as (tubing A), not quite as flexible, but far better performing...
In general terms, materials that are more flexible have greater permeation levels, and through use (and permeation), the polymer chains get "stuck" and will not move as freely - thus, the tube gets brittle. The more rigid the material (usually), the more structured the chains, move out of the way of the gas less easily, and have a lesser permeation. The (bev. Tubing) offers some of the best of both worlds, still rather flexible, but with a good barrier to permeation due to the crosslinked liner."
My "tubing A" and "tubing B" are both PVC. Both are pliable, but the one I run up near the tank feels just like silicone. I essentially get both for free and replace them frequently even if they seem fine.
Just recently, I decided to pose the question to one of the leading manufacturers that I often deal with at work. My concerns were permeability, as well as "brittleness" with prolonged use. I use two of their other products currently and asked how they stack up.
----- I'm posting this with their brand names removed, as to strictly convey what their technicians responded with. I'm not trying to push a specific product. I just happened to find their response interesting, informative, and worded in a way that was easy to understand. -----
"Thank you for your interest in our products.
Please find answer below from our technical team -
OK - for general, low pressure use in conveying C02, the (tubing A) and the (tubing B) are good economical choices. It will become somewhat brittle over time, and there is a level of permeability to most gases due to the plasticizer used in both, inherent in most flexible materials.
The best choice would be (their version of "beverage" tubing), not only is it a polyelfin liner, but since it is cross-linked, there is far less movement of the polymer chains as they are "linked" together. Of course, (bev. tubing) is not nearly as economical as (tubing A), not quite as flexible, but far better performing...
In general terms, materials that are more flexible have greater permeation levels, and through use (and permeation), the polymer chains get "stuck" and will not move as freely - thus, the tube gets brittle. The more rigid the material (usually), the more structured the chains, move out of the way of the gas less easily, and have a lesser permeation. The (bev. Tubing) offers some of the best of both worlds, still rather flexible, but with a good barrier to permeation due to the crosslinked liner."
My "tubing A" and "tubing B" are both PVC. Both are pliable, but the one I run up near the tank feels just like silicone. I essentially get both for free and replace them frequently even if they seem fine.