Couple of kegging/CO2 related questions

Hey Guys:
New here, but glad to find the board. My girlfriend and I are just getting serious with the brewing hobby and I had a few questions about our setup that I figure you all might can help on.

First, we brewed some cream soda from an extract (Gnome) a week ago, and it has been in a corny all week. However, when I hooked up the CO2 and tap hose, it came out super foamy. Which I thought was a decent sign, but apparently not because as soon as the foam dissipates (which is pretty quick), the stuff is flat as can be. It tastes pretty good, but the flatness ruins it obviously. So, I thought I'd try and force carbonate it. I called my brew shop and they said to actually hook the gas up to the OUTPUT of the corny and throw some CO2 on it, then shake it. But, I think I didn't have enough pressure on the regulator (~12 PSI) and when I hooked it up and shook it, there was so much pressure in the keg that it actually shot the cream soda BACK through the gas hose and started spraying out of the regulator. A lovely mess, I assure you. I felt like a real *******, to say the least.

So, I disconnected everything, bled off the pressure, and then re-hooked up the CO2 at ~10 PSI and it seems to be sitting OK, but is still flat. Have any of you guys brewed cream soda and have any advice for me?

Second question is that I just kegged a pilsner that we brewed, which has been fermenting for 2 weeks @ 48F in the kegerator. I added the 3/4 cup of priming corn sugar, and rolled the keg around gently to mix it. I then put it back in the kegerator and dropped the temp down to ~36F. The recipe is a clone of Saint Arnold Summer Pils, and the recipe doesn't say how long it needs to sit in the keg/bottle before it's ready to drink. For this type of pilsner, will it ferment/carbonate with the sugar at such a low temp with the CO2 hooked up at ~10-12 PSI? Or should I take the keg out and let it sit at room temp for a few weeks with no gas line hooked up? Do I need to shake it at all?

Last question: As a general rule of thumb, anytime I hook up the CO2 line, should I bleed the pressure in the keg first? Sorry for the rambling long post, but I certainly appreciate any help or advice!

I don't do soda and I'm on my way out the door so:

Adding priming sugar to a keg is a fine way to get natural carbonation...but it ain't gonna happen below 70 degrees. That's too cold for the yeast to ferment the sugar and produce the CO2 for carbonation.

Get it off the gas and let it sit for 3 weeks at 70 degrees...just like bottling.

Don't shake it.

Add some CO2 to every keg and burp it...this purges the O2 out.

Someone else can pick up from there.

Soda is easy..........but it needs to be carbonated at a very high carb level compared to beer. I keep mine at about 30-40 psi. This means that you need a very, very long beer line to avoid foaming. I have about 30 feet on my soda keg, at 40 degrees, at 40 psi. It's fine, then. If you don't want to force carb at such a pressure, you can always use plastic 2 liter soda bottles to bottle in, using yeast. If you keg soda with priming sugar, it'll carb up, but go flat as soon as you start to serve it if you're not re-adding the co2.

Soda will be FLAT at 10 psi, that's for sure.

Biermuncher answered the question about the pilsner. If you want it to carb up, keep it warmer for three weeks, then cool it.

Seems like some great advice so far..
Lastly clean your regulator out really really really really good. You don't want anything growin in there and infect your brews.

I just made some of the same gnome soda about a month ago. I let it chill at 38 degress for a day or 2, then hooked up the gas line at 32psi and left it. It was fully carbed after about a week and a half. I have 15 feet of 3/165ID tubing on my soda keg and it seems to pour fine (a little fast, but nothing that's not manageable).

And don't gas it up through the beer out post! Some people reckon that bubbling the CO2 through solution helps to carbonate it but this is rubbish to be honest, just set a high pressure and leave it. Using the beer out post to gas it up can lead to problems (as you have discovered).

Thanks a bunch for the advice, guys! I will post an update once I see some results. Great forum and I look forward to pestering y'all further. seriously though, I'm doing my best to learn as much as possible, and I appreciate the help.

Of course you mentioned releasing pressure before putting it on the gas- that's the way to do it to prevent liquids from flowing back into the regulator and ruining it. Also, if you can buy and install some check valves, that will help to prevent this from happening again.