Hi all. I know this is an old post, but still...I have been a few months now looking for solutions to a similar problem than the one explained by JayHarvey in the previous post.
The thing is, I wanted to fill my 5 gallon Keg with 2 liter (=67,6 Oz) diet cokes. I am carbonating at 25 psi and 40º, and no matter how long is my 3/16" line (I tried from 10 to 60 or more feet, nothing worked), that the final result is a completely messy and foamy dispensing. I use a Perlick flowcontrol faucet also (I tried different options, none worked). I mantain both the line and the faucet in the same temperature as the keg.
But here is the shocking point (at least for me...): I use the same set up with just carbonated water, and it works just fine. So I think the chemical / ingredients of the liquid play a very important role in the decarbonation of the liquid. I guess the diet coke from a 2 liter bottle have just more nucleation points where the bubbles can grow...
Any ideas on how can I make it work?