That's good to know it will read between 900-1000PSI until it is empty.
Why will it only read 500PSI in the fridge? That might be what is happening to me...
I started troubleshooting with this newly filled tank because I suspect I have a leak. I pressurized my whole system and turned off all the valves to isolate the leak (including the tank valve). So I freaked out that the tank didn't get filled all the way when I saw the tank gauge reading 500PSI. I wasted a *little* bit of CO2 tonight, but not that much!
As for the leak, it looks like it is happening with two different primary regulators. The rest of the system appears to be holding pressure. I am concerned both of the primary regulators are leaking at the interface for the tank and primary regulator. I've got that connection as tight as it will go. Any ideas why this would have started leaking all of the sudden? Could something be wrong with my tank?