I would go with "Whatever is easiest to fill/swap" Around here 20lb tanks are swappable at several "Grow stores" for ~$23, the 5lb are a hassle to get refilled. So for me, I went with 20lb, I picked up a few cheap and swapped them out. Where my daughter lives, there is a LHBS that fills/swaps 5lb tanks, so when I built a system for her, I did a 5lb tank(she and her fiance drink less and get pre-carbed stuff).
MJ became legal in MA some time ago, so all the stores carry CO2 tanks for indoor growing(bigger yields?). depending on where you are, maybe take a look.
Kevin
MJ became legal in MA some time ago, so all the stores carry CO2 tanks for indoor growing(bigger yields?). depending on where you are, maybe take a look.
Kevin