If you go to the local welding shop and they are willing to fill your bottle (vs. exchange) if they ask what you are using it for say that you are using it for live bait on your bass boat. Some shops will back off if they suspect you’re using it for aviation even though (as stated above) there is no longer any difference between ABO and “regular” O2. With the current air separation process all the moisture is removed early on. It’s all 99.999% O2 with trace other gasses.