Is this really a thing?
Its my understanding no. Bad co2 has more to do with a contaminated tank, not the actual co2
Man! You post A LOT!
thanks?
passion for perfection…love it.
That was unnecessary.
You’re assuming I didn’t google this first? One benefit of this forum is that there is an elimination of noise and suspect advice (things a Google search will give you as it relates to brewing).
Now play nice and contribute or just ignore my constant posting! 
forum is here for questions, with lots of people willing to answer.
carry on Justin 8)
+2
Justin, I love the noise reduction comment. Carry on
I swap tanks at AirGas, and I’m pretty sure they have stickers on them that say food grade (I can’t check right now though).
Whether or not it really means anything, I can’t say.
I was told by an industry person that the only difference is the price you pay.
So do tanks get contaminated over time? One more thing to obsess about…
That’s why I didn’t get anything through to the NHC!
Not as likely if you have check valve installed- preventing back flow of beer in regulator and tank.
Ok after scouring the Internet (bless my sales job without an office) I’ve come to the same conclusion. Cintas fire folks mentioned they fill for Pepsi locally, good enough.
Food grade tanks are properly purged by the dealer and then refilled. Welding grade tanks are typically refilled without purging. The carbon dioxide going into the tanks is the same, but what comes out could be different because of the differing purge procedures. I use welding gas grade.
^ I didn’t read this, but I did read the only real factor is the tank. Paintball tank? Probably an issue.
They need hydrostatic testing every so often (what is it, every 7 or 10 years?). If you are swapping out tanks at a gas services company, it shouldn’t be an issue.
You definitely want to make sure you have the proper check valves in your system.
Certified by a hydro test every 5 years.