I am using a crude yeast and sugar water mix for C...

To be honest you are wasting time energy and money doing it like this , it's not that it's not beneficial to have a CO2 system but typically CO2 systems are for either grow rooms that are way way way to hot (30c and up for the most part) or the room is enclosed in such a way that it don't receive new air from another soure (outside your grow room) With that being said I don't know exactly how your set up in the sense if you have intake fans/exhaust fans how ever even if your room is enclosed and you are running your DIY C02 system you may wanna consider different options for various health reasons , the last thing you want is for that to be blowing mould spores and other types of spores around your grow room so I would advise against this method but if your not running into that type of problem because you clean it and change it often then thats ok too . I personally would go invest into a small C02 system for your grow area they arent expensive and they are far more effective . You also gotta keep in mind again that C02 is most used up when the plants are too hot and can't "breath" . I hope this information helps you understand the "when" someone should use a CO2 system and the risks you run when doing it with that type of DIY set up . -Happy Growing!