hey man hows it going..
here is my suggestion, and i suggest this based on my many years of using this method.
convert your room into a CGE or closed growing environment which simply means no in or out vents and the room is completly sealed off.
however if you do chose to do this you need to make shore you have a way to cool your room and warm it when needed. this will allow you to completly completly control your growing environment and also will not allow pest, fungus, or any diseases in your room.
now for the co2 part the only thing you will have to decide is whether you want to use bottled co2 with a regulater or a co2 generator..
the only reason i would not use a generator is if your room already runs hot (above 7
because the generator will add heat to your room..
i personnaly have always used multiple propane generators because they last longer than bottled co2 and i have huge grow rooms..the enitial cost for a generator and a controller is more than buying a bottle with a reg. but in the end cost less.
when doing a cge environment i always use a carbon scrubber powered by a large inline fan and simply set it up in the room and let the air recirculate in the room as this will clean your air..
in doing this you will be able to always keep your grow environment at 1500ppm and not waste any of your co2..
if you have any questions hit me up.