Co2 bag too much for my growbox?

I have a grow box about 4feet long 4feet high and 2feet deep. About to enter flowering stage wanted to try out one of those CO2 bags don't know much about them at all is too much for my small grow area I do have fresh air fan blowing only when the lights are on and a 4-inch inline fan filter on a timer that comes on for 5 minutes every 30 minutes to keep humidity and temperature down

Everything I have read about those bags is that they are useless.

Something that size you may as well just go with sugar, yeast, water and make your own.
I can't see those bags being any better. I've bought a couple but haven't bothered again....

Compared to using a co2 tank the bags suck... but if it's all you have then it's better than nothing. I stopped using them when I started getting an unknown powdery mold on my medium that was happening at 20-30% rh. I never had that before and it stopped after I stopped using the bags. The mold never spread to the leaves and did not effect yield or taste. I think after a while the mold in the bags get out and start trying to colonize your medium.

Thanks for the advice everyone I think I may try to go with one of those bags just to see if I have more growth and hopefully a bigger yield. read up on it a lot today the science behind it makes sense also seeing a lot of videos on YouTube on how to make home CO2 bucket with a air pump mushrooms and coffee grounds may do that in future grows if I see results from the bag