Calcium reactor and Paintball gas

[Mumbo_Jumbo]

Hello, i have a small calcium reactor, its the acro-cal. For 10 to 75 gal.
I was wondering if a CO2 paint ball 12gr tank, will be usefull for this calcium reactor, i have a paintball gun wich i never use so i could use the tank for something!, will it work?
If not wich kind of CO2 tank can i use, my LFS have not an idea and the only other CO2 tanks i know are the 6kg hospital CO2 tanks, way to big for my aquarium, (20gallons).
Any suggestion its accepted.
Thanks in advance.