OK. So I've been kegging since 12/11. I got a new bottle of gas right before Memorial Day 2013. I brewed 2 beers for Memorial weekend, a Blue Moon clone that I've made 4 or 5 times already, and a Two Hearted clone that I've made before as well.
I kegged the 2 beers (that is all I had kegged) and put them on the new gas to be ready in time for Memorial Weekend. On Memorial weekend I pulled a glass from each and discarded like usual, then tried the next glass.
Both kegs had a bitter taste to them. Even overpowering the 2 Hearted hops. I basically got depressed and left the beers in the kegs until a month or so ago when I got time to brew again. I dumped everything and cleaned my kegs with 180 water and unscented Oxy just like I've been doing all along. I also pulled the dip tubes, and unhooked the hoses and picnic taps for a Oxy soak. I did the smell test afterwards, and everything was good to go.
I kegged my 2 new brews last week, OctoberfAst and a brown ale. I tasted the gravity samples of both of them to make sure I wasn't screwing something up before kegging, and they both were spot on.
I just pulled a pint of each, and the horrid taste is back.
So, do you think the CO2 I got could be contaminated some how? Could there be oil in it, or something weird? How can I check it?
I am thinking about kegging 5 gallons of distilled water and putting it on gas for a week to see. I have a 4 keg system, and I have 2 brand new lines and taps that I can use to eliminate the possibility of contamination.
It just pisses me off that I essentially wasted another 10-12 gallons of beer.
Edit: I carbed this over a week at 12psi or so, and that is how I carb everything. I read about carbonic acid from force carbing, so I don't think I have that. Also, I did NOT taste the old beer to see if the taste had dissipated before I dumped it, in case it was in fact carbonic acid, stupid me I know.