Originally Posted by Bobby_M
The systems all include a screw on regulator and a stainless diffusion stone. Some have a flexible hose to connect the two and some have a solid stainless wand attached to the stone. I like the idea of the latter to keep the stone where you want it. Those regulators are probably the most marked up piece of brewing gear there is but there just doesn't seem to be a cheaper to get O2 out of disposable tanks.
Look and ask around as there are many legal owner owned bottles out there, sure a exchange plus a fill charge will cost you but again many times cheaper than those HD disposable bottles. Besides the big savings you have an investment that you always can sell.
I've picked up owner owned Linde 260 cu/ft O2 , Argon and Helium down to I believe 70 cu/ft for a matched set of owner owned "Q" bottle O/A units from $10 260 cu/ft to $45 a pair of "Q" bottles with papers. Besides used for heating and bending steel with a rosebud the O2 bottles with Victor regulator and a medical L/minute flow meter are great for adding O2 thru a stainless stone in the fermenter. Refilled larger bottles keep the cost per cu/ft way down vs those disposable bottles. My way of thinking if you plan on brewing a long time including 150 to 215 cu/ft Nitrogen/Co2 stout gas bottles. Co2 20# are common and cheap to collect.