What did I do to my keg system?

Hey all, need a little help here. I built up a kegerator system a few weeks ago, and I hadn't heard about how to "balance" the system. Anyway, I bought 15ft of beer line, and just split it between the three taps - So I have about 5 feet of beer line for each faucet.

I hooked up 2 kegs that I had previously conditioned, and tried it out. the beer was pretty much as carbonated as I expected, but I didn't think I was getting enough (or any) head on the pour. Intuitively, I figured that If I increased the CO2 pressure (was at 9, increased to about 12), I would get slightly faster pours with a little more head. It worked to an extent, so I bumped it up to about 17 and the pours were right where I wanted them.

I knew that by doing this, I'd be forcing more carbonation into the beer, so I did some checking online - that's when I found out about balanced systems. I read that as long as the CO2 pressure was set somewhere between 6 and 19 or so you should be ok - so I left it alone.

All is well. A couple weeks later I started getting a little too much head on the pours - I assume that the beer now had a little too much carbonation, partially from force and partially from the remaining conditioning. So I set the pressure back down to about 9. When my friend poured a beer the next day, he got nothing but foam. I'm guessing that by decreasing the pressure, I let CO2 out of solution (like opening a pop bottle). But now I don't know how to fix it. I don't know whether to up the pressure back to 17, and let it down slowly, like 1 psi per day - or weather I should vent the keg for a few minutes, or what? Any help is appreciated.

Did you vent the high pressure after turning down the regulator?
It sounds like you overcarbed your beer while at the high pressure. Try turning it way down like 5psi for a couple of days.

Right, you have to vent the kegs when you try decarbing. It takes a few times over a couple days.

If you're at the carb level you like but you want more head to form, hold the glass a little lower as the beer pours.

It took awhile to get balanced with mine as well. I keep it on 12 psi and it is about perfect but I struggled with the over/undercarb thing because I tried to fix it too fast. Even now, I have to clear the line into a paper cup before I fill the glass or I'll get too big of a head. I guess this is due to the different temp of the beer in the line. Of course in pro establishments, they just let that part run down the drain.

Good luck,
Al