I have not got my whole keg set up yet but i have been browsing around so today i just picked up from a gentlemen on craigslist a completely filled 20# co2 tank. He said he used it for guiness kegs and the tank is a co2 nitrogen blend does this sound right?. he said he used it for a few home brews his buddies made. Iam jusy curious will this be ok for me to use with various types of beers? either way im not at a loss because i paid 50 bucks for the filled tank and a dual gauge regulator. But i would like reinsurance that i can put this to good use