OKRED,

There is more co2 because you are dealing with a compressed liquid versus a compressed gas. As you use the co2 you draw co2 vapor (gas what ever you want to call it) from the head of the tank. As you use more of the gas more liquid co2 forms co2 gas. The co2 will remain a constant pressure until you are almost totally out of co2.

A 5lb co2 tank is a lot smaller than a scuba tank right, so your break down might be correct there, but if you get a co2 tank that is closer to the size of a scuba tank, a 20lb maybe, you will be able to get more uses out of it than the scuba tank. <img src="/forums/images/graemlins/smile.gif" alt="" />