Originally Posted by VITARTE
If it makes you feel better (but, then again maybe not so much) most if not all C02 tanks used to carbonate soda fountains are filled in in the same shops that welders use to fill theirs.
So I would assume that if its safe for us to drink, fish shouldn't have any problem other than us overdosing on the C02.
Not quite that way in Canada. If the CO2 is going to be used to power/drive beverage dispensers it must be medical (suitable for human consumption)
grade in Canada. Therefore, I get my tank filled at the local Coca Cola distributor. No worries about quality, done in 10 minutes in my own tank (no exchange) and 35% lower price than a welding supply store. The welding supply srores are exchange (old beater for my newer tankl) or wait at least a week for the tank to go to their plant and return.