I have a 5# Co2 tank I got from a welding supply. they also rebuild regulator so he threw that in also all for $50. I run it at a little under 1bubble per second. I use a air stone at night. Also running high led lights and dosing fert customized to my tank I got from a guy on this site. This was my first planted tank. (I am starting my 3rd now) Lots of ups and down with this one. Just a matter of getting all the right combination.