Found one, it said if your room is about 594 cubic feet which mine is, you'd need to emit c02 for 21 minutes to reach the desired 1500 PPM.

As for how often I would need to do that to maintain a nice level of c02 in the air, that would be something I'd have to play around with I guess.

Every few hours should make a good difference in yield I would have to assume? I will have small leaks, as the door will let some air out, but not a ton should be leaving the room with huge speed as all exhaust will be off, right?