Diving oxygen cylinder for CO2?

[NoMoreGoldFish]

My brother just upgraded his oxygen cylinder for diving, so he has a spare one lying around. This thing is huge compared to most CO2 cylinders for aquariums, I was wondering if I could fill it up with CO2 and integrate that into my setup?

Has anyone ever done something like that?

 

[starquest]

I'm going to jump in here and say that I see no reason why you couldn't do that. I'm a retired respiratory therapist, and dealt with all kinds of gas cylinders, in my day. The only thing is, that you probably couldn't use a CO2 regulator on an O2 cylinder, but you use whatever type of regulator is made for that cylinder. All the regulator does is to register the tank pressure in lbs/sq.in., and then step that pressure down to 50psi in order to make it useable for a CO2 flowmeter, and that you can probably purchase in whatever degree of sensitivity that you need for the flow for your tank.

 

[starquest]

I meant to add the caveat that I don't know what the federal regulations are for that. You would have to research that part of it, whether it is permitted to put CO2 in an O2 cylinder.

 

[NoMoreGoldFish]

Thanks for the quick response. I just talked to my brother and he says the type he has aren't meant for liquid and I think compressed CO2 comes in liquid form. I think I may have found a cheaper/safer alternative in CO2 fire extinguishers. I found a 2.5 gallon one for less than $60.