So I've been researching getting my C02 tank filled and I'm hung up on the grades of C02 that are available. Anyone have any input or knowledge of what is safe for use in kegging. I just want to understand what I'm using in my keg before making any decisions. I don't want to harm anyone with the wrong grade of C02 when I can spend a little more on the correct gas. I've read a few things like Food/Beverage grade is different from industrial grade, Beverage grade is an up sale and not necessarily needed, and Industrial grade could contain impurities/carcinogens? I've read that it's the same gas other than the tank it's held in as far as the tank is cleaned or flushed/maintained. If my used tank was previously filled with a different or lesser grade could it be contaminated? I'm not like a super health freak but like I mentioned I just want to understand what I'm using and that it's relatively safe to use. Thanks!