Carbonating Stone with 1/4" Barb, 0.5 micron are now in stock.
http://www.mybeerandwine.ie/home/311-carbonating-stone-with-14-barb-05-micron.html
Simply attach one end to a couple of feet of 1/4" 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. Carbonates your beer overnight.
Are you sure about the pressure?
You start at 2 psi and say in an hour raise to 4psi and so on. Slowly raising the psi maximizes absorption