I agree with the fact that perhaps making a external CO2 diffuser out of glass is not needed (extra costs and more chance of breakage). I do like the idea of being able to do C02 misting externally; IF it works well. I personally am trying to keep as much equipment out of the tank as possible. I like the clean look inside a tank. No heaters, powerheads, cables, etc. That is why I have been using CO2 reactors instead of diffusers. Of course, there may be tradeoff doing that. A nice clean look with not optimal performance.

Wether this external CO2 diffuser actually works is to be seen. Is it equivalent to having the diffuser in the tank? Do you lose performance by doing it externally?