I use co2 tank and reg. I like it. Huge difference from when I didn't use it. My temps are low 70's. I don't care what anyone says, imo, plants use co2 at any temp. I mean sht, we'd have some huge problems in this world if plants only used co2 between 80-85F. But ya I use it and like it. Some believe the Earth is flat, I think its round! Try it. If you like it then great, if you don't then sell it. I picked up a co2 reg new on Ebay $40 with shipping....it outlasted my POS Hydrofarm junk. If you can find a tank cheap on craigslist...and don't like it, you'll have your money back in a week.