For me, I added CO2 on my first grow. My temps were running a bit high but perfect for CO2 grow so I used it to balance out the situation. Was easy enough to setup and get going. I opted to purchase 20lb tank so I could just refill going forward. I also bought a cheap dial timer and run it first 15 mins of every hour while the lights are on. A few grows in I may upgrade and add a controller to keep a consistent ppm at all times while lights up.
Too many pics, journals, and info online and via trusted sources supporting higher yields with CO2 for me to ever consider a counter-argument. However, it is not a freebie. You do have to have shit locked in to get full gains from it.
