Is all Co2 the same?

Since my LFS thats closest to me just shut down today, im now searching for other spots near by to refill my pressurized Co2 bottles...

Then while searching for stores, i read that over here at least, you can get Co2 refilled from certain stores that deal in fire fighting equipment, and was wondering, would that work or are would there possibly other gasses that could potentially br mixed in?

I know may sound like a stupid question, but really dont want to risk losing a whole colony of high grade crystal red shrimp...

Thanks

Thanks for the suggestion, i was planning on calling some gun shops tmr actually... Although over here people are more into Air Soft guns / BB guns, rather than paintballing, so still a bit hit ot miss if the shops near me will have refilling services available, but definitely worth a try...

^ yeah, over here though a lot of shops have closed down over the years due to soaring rent and property prices, and im not sure the few gun shops near me will have Co2 refilling options as stated.... Especially since most are quite small...

Also, after some looking into it a bit more, there seems to be several grafes of Co2 including food grade / industrial grade and some other grade of Co2, although not sure if they really make a difference...