thanks for posting this. i have a question:
what size barb are you going to use to input the co2 line? the smallest one i could find that would fit into a design such as this is 1/4" (i think).
i am planning on running standard co2 airline tubing from my bubble counter to my reactor; obviously this isn't going to fit onto a such a large barb. thus, i think i am going to simply drill a hole and input the tubing directly, either with an airline connector thingy (a la ghori from aquabotanic) or without (a la rex).