I decided to hook up an old co2 tank in my tent and do not have a controller yet. it's a 4x2x5, so 40 cu. ft. i found CO2 and YOU so i'm guessing i need .06 cu ft of co2 injected, but i have no idea how much that is. ive got a 20-30lb tank with a decent regulator. my questions are, how much...