TKE wrote:Should I turn my regulator down to serving pressure and keep it there or turn it down when serving and then back up when not serving?
No, you should set it to the equillibrium pressure.
Will keeping it at the lower serving pressure cause a decrease in the beer carbonation over time?
If your beer has equillibrated at 15 psi, and you decrease the pressure to 10 psi, the carbonation in the beer will decrease to this new equillibrium. You need to set the regulator at the pressure that puts the proper amount of carbonation in your beer (once equilibrated) for the temperature your kegerator is set at. Then, don't touch your regulator. If your beer is having foam issues, then your problem is the length of the beer line.
I'm of the school of thought that if you can't just wait an extra week for your carbonation to equillibrate, then you just need to brew more often.