Hi. I’m new to this and I have some basic questions. If I buy a C02 tank, over time, do I just get it refilled or do I exchange it? I used to weld and oxygen tanks (and other gas tanks) were just exchanged at the welding supply dealer and refilled whenever they got to it. You didn’t really own your tank, you paid a deposit on the first one you were given and your deposit was returned whenever you surrendered the last one you were going to use. If I buy a tank and it is refilled on multiple occasions, doesn’t it need to be pressure tested at some point? Also, is the C02 used in brewing a special grade or purity or is it the same as used in industrial applications, fire extinguishers, etc.? Where do you go to get a tank refilled? Thanks.