I am considering priming my keg to naturally carbonate instead of force carbonating it. Once I serve from the keg how much pressure should I keep the keg under to make sure it doesn't go flat?
just follow the set and forget setting for your serving pressure based on a carb chart as if you were doing it that way, if you carb to 2.4 volumes naturally, then set your co2 pressure to match that at the given temp.