so when to talk to the fire dept.'s today, the chief told me he would find me a tank, and hook me up with fill, if i did some volunteer work { no prob as I already do plenty of that with the soup kitchen, 4H, etc...} they fill there tanks to 4000, so on a disco running at 2000 does this mean i will only 2 fills per tank fill?pus what about paint ball tank at 4500 psi, will they work for intended purpose?or can I use a big ol' co2 tank, and fill it with air???