If you're able to consistently bring in fresh air, adding in CO2 isn't going to produce any better results.
But if fresh air isn't always possible, then CO2 can assist.
The yeast jug works, ex-hale bags work, propane generators work, and of course a tank of CO2 works well too
Well, they are in the closet in a room they have all to themselves... I keep them in the closet in case anyone stops by that I don't want to know I'm growing. Like for instance my girlfriend's niece likes to snoop around when she's here lol like any 10 year old lol so it helps to have the option to close them in. But 99% of the time the door is open to the closet and they have a fan blowin' on them and our central air is at 72 and it stays way cool in here so I think they are good without the extra CO2. They seem to be thriving pretty good so far. Just starting their third node. One is growin' a bit faster than the others but I'm not concerned about it. Thanks for the reply TBM!