CO2 help.

Its lower at daytime since the plants use it. You could close the window to get it to around 600ppm (thats the average indoors) CO2 Bags and what not dont really work unless you use like comically much and a closed system. The most viable solution is to use a gas tank and a controller that can time the release to keep it at a desired level. Challenge here is the heat. Not for the plants but they place the tent is placed usually. Having a Lungroom is recommended. Or you have a really cheap supplier of CO2 Gas Tanks/Refill then you can just keep the windows open.

Close your windows and buy some cats and let the cats live in grow room also you can keep your window closed and have your grow in the same room you sleep in. Co2 is 400-450ppm outdoors in the USA. A closed bedroom with someone sleeping in it can easily exceed 1500ppm from just one night of sleeping in the room