Hal I have not used the bags. I've used dry ice and yeast bubblers. I never set it up as a comparison study so I really don't know if it had an effect one way or the other. That's something I should do in the future, though it would be difficult to set up a "no CO2 added" vs "CO2 added" and keep everything else the same. I'll have to think about that. Your plants look nice, and you may well be getting a boost from the bags. I just tend to be skeptical because I've seen people with decrepit grow setups and weak plants who spent more time and energy on getting added CO2 than on just taking care of their plants properly. Obviously that's not the case with you, so you may be in a perfect position to benefit from it. Keep in mind, however, that plants in the early-mid growth phase can grow very fast, even with no additional CO2.