I have 2 corny kegs hooked up to party taps in my beer fridge. When I draw off a beer the line is full of clear beer but once I close the tap the beer slowly filters back into the keg and the line fills with air/c02. I can't tell if it is co2 coming out of suspension or not. I know there are not any leaks in the lines and can only see it on one line since the other is black. Is this normal or can I some how fix it? I think it might be causing a little extra foam from when the line fills with beer. I thought once it was hooked up and filled with beer it should remain there. Thanks for the help and any suggestions.