just turn the tank on, with all regs backed completely out, then off with the tank valve. check it in 12 hours. then another 12. and another 12... until the tank gauge reads zero. if you get less than 2-3 days, something is WRONG! then set one reg at a time to say 15 psi WITHOUT serving co2 to anything but disconnects and with tank off still. same 12 hour intervals. if less days than before and this gauge is zero, that is the problem reg.
"Back when I was in the pen, I used to beat my meat..."
"Damn ye, yellow-bellied sapsuckers; I'm a better man than all of ye milksops put together" - Blackbeard
"...I have really good sex moves; that I learned in China. I'm a sexual tiger; and feed on va-gine-a." - Jon Lajoie