How much a difference will a CO2 bag make?

Co2 can give you around 30% more if used right ECT .... Need an air tight environment that's all controlled. Works best first 4-6 weeks of flower. Hope this helps! https://www.growweedeasy.com/co2

Co2 can make a huge difference with 2 caveats: you need strong enough lights to utilize it, 600 watts is probably the minimum, pointless below 400 watts. Second caveat is you need enough co2, I’m my experience co2 bags only raise co2 100-200 ppm to about 600 ppm, far shy of the 1200 ppm recommended for optimal growth. Going with bottles co2 with a regulator, while more expensive will give much better results.