Hi New_from_Peru if you bought brand new from J&L, cylinder is hydrotested from factory and is good for 5 years (+ /- couple of the months) you need to fill and pay only for CO2
If one tank is 20’ away from CO2 distribution center, you are need two separate needle valves and two bubble counters and high grade (CO2 proof) tubing to supply proper amount of CO2 for diffuser or CO2 reactor