Carbonates 5 gal keg in 15 minutes. Carbonating Stone with 1/4" barb: Carbonate your beer just like the pros. Simply attach a couple of feet of 1/4 inch tubing to the end of the dip tube inside of the keg, and the other end to the Stone. Make sure you attach hose clamps to both connections. Then set your regulator to about 2 psi, and the gas will be forced through the millions of tiny pores in the stone, which dissolves the gas into the liquid.