It should be great for CO2, but many have used silicone tubing for years without issues. I'm sure you could find a metal check valve for your pressurized line if you're worried about plastic not holding up to the pressure, or buy some reactor or bubble counter with a built-in check valve. Notice a search for "check valve" on that site gives a popular reactor: http://www.drsfostersmith.com/Produ... valve&Ntx=mode+matchallpartial&Ntk=All&Nty=1
Discussion on the krib: http://www.thekrib.com/Plants/CO2/tubing.html
HTH
Discussion on the krib: http://www.thekrib.com/Plants/CO2/tubing.html
HTH