Oxygen regulator

I just bought this threaded diffusion stone from MoreBeer:


And I have a disposable oxygen tank with this regulator:


The inlet for my threaded stone looks to be 3/8" or 1/2" un barbed, and my oxygen regulator has a 3/16" barb. What is the best way to attach a hose between the two? Is there another regulator out there that has a removable barb to put a bigger one on?

Also, is there any disposable tank regulators that has a LPM gauge, or does anyone know what LPM these regulators run at?

i just went through this ordeal. my solution was a union reducer (in whatever size you need) from Grainger or ebay i also did away with the disposable canister and bought an 20 cubic foot oxygen tank and regulator from harbor freight. i got the wand from morebeer with the stone on the end. it took a lot of back and forth to the store for hoses, reducers etc but it works great now. i didn't want to be guessing how much gas was left in those little canisters or have to dispose of them, i figure 20 cubic ft should last a good long while.