How much of a difference does adding CO2 make to y...

Hi bro ! Co2 is a damn yield increaser ! It also allowing you to grow with higher temps like 35°C without any issues for the plants ! The problem is that the real effective solutions aren't really cheap , it is the oposite & you will have to change many things in your setup , like the airflow control : no fan or extractor when you spraying co2 ! Co2 is much for the commercial growers & people who can spend a lot of money in their hobbys ! Hope it will help you to see clearly 😁

Only you can answer if the cost is too much or not for you. But unless you are using a closed grow space I would not do it, since you would be exhausting the added CO2. You could try to take advantage of the CO2 that people produce naturally and route it to the grow space; do you know that CO2 levels rises quite high during the night in bedrooms? There you have a free source of CO2, just get your tent inside your bedroom, or exhaust your bedroom to your tent.