Co2 kept going up

[damianinpa]

All,
I bought a Cannonball keg and changed out the corny lid with one that has a carbstone. Last night was first time I used it. I set the pressure to 12 psi (Using 74G cartridge) and put in Fridge. Checked on it an hour later and it was at 25 psi!. I did purge it a few times and again set to 12. Went to bed and looked this AM. Beer on the bottom of my fridge and the regulator shows 5, but, I think the CO2 is out. My guess is it went up again overnight and was at high pressure. What can cause this? Bad Regulator? Bad seal of the corny lid? I'm not sure what I did wrong. I'll have to taste the beer tonight as I have no idea what state the carbonation is in. But, I really don't get how the CO2 and increased greatly on it's own which is why I'm asking for help. This was my first Keg try.
Damian

 

[day_trippr]

Don't know anything special about the type of regulator you must have used with the small cylinder but it isn't uncommon for a conventional (cga320 style) regulator to require some adjustment after being placed inside a cold fridge for awhile.

That said, the pressure drift is typically in the low single-digits; doubling the pressure seems way out of scope for that phenomenon. And there's nothing downstream of your regulator that could have caused that, I'd suspect something functionally deficient with your regulator...