homemade Grow Box Needs Cretique

[M.B.A.]

So what wil the c02 do for the plant? ie make bigger, tighter, or just better? On my set up I have good air flow or dose that mean i dont need a set up like this?

Plants breath in CO2 and expell O2. But anyway, I used this method before in the beginning of my grow, seemed to work. got great results as you can see from my threads