Wow, this is quite a long thread, all about co2 too, how cool.
As I read this thread, I assume you've pretty much conquered all the other aspects of your grow room?
Because co2 should be about the last thing you look at. I also assume that you are using HID lighting and not cfl's?
Adding supplemental CO2 will benefit the plants only if they are CO2-limited. Which means that, at ambient CO2 levels, the canopy is light-saturated. This is pretty difficult to achieve with CFLs.
Once you've gotten everything else dialed in, and you want additional co2, you wouldnt bother with these home made brews, it's a waste of time and energy.
Peace