How often to replinish CO2 in grow room/How much and how fast do plants use CO2?

I am thinking about possibly adding co2 to my future grows. I know I want about 1200 ppm of co2 in the room. my grow area is 5x9x7 feet or 315 cubic feet. So 1200 ppm in 315 cubic feet would be 0.0012 x 315 = 0.378 cubic feet of co2. Now, how do I maintain that level constantly? Do I just put .378 cu ft in the grow area everyday once a day? Or would the plants use all that co2 up in 30 minutes? How fast would say, 8 plants in that space use up 0.378 cu ft of c02 and how often would I need to replace the co2 to maintain 1200 ppm (or 0.378 cu ft) in the grow area?

that really depends on how well your room is sealed. a ppm co2 monitor is the only way to tell.

what about if the rooms is completely sealed? or very very close? i am also curious how quickly plants will use up the co2 in a room

you can find info somewhere about settings/timings but anymore I rely on ppm controllers.

dbkick, how does your situation play out? How many plants, what size room, how much lighting, how much co2, how often do you replenish co2, what method of creating co2, etc...? Basically, how do you deal with using co2 on daily basis?

i run 15 ppm every hour for 15 mins and i dont turn my fans on for 30 mins after i start co2 so its 15 mins of shower then 15 mins of sitting. then the regulator goes off and my exhaust fans turn back on. all on timers. its pretty nice not having to go in there every hour but i usually check on it anyways just to make sure everything is working right.