I’ve transferred my first lager, Bohemian Pilsner, to one of my King Kegs from the fermentation bucket. Purged the KK with CO2 before transfer and gave it a puff of gas (about 5 p.s.i.) before starting to lager at 1C. I noticed the pressure has reduced to zero on the gauge so pressurised to 15 p.s.i. Now, a few days later the pressure is back to zero, obviously the gas is dissolving into the beer. I’ve not read anything about maintaining gas pressure until after lagering when carbonating. Should I leave it at zero p.s.i. or keep adding CO2?