Dirty CO2 and/or tank. Does this make sense?

[collinsDPT]

Guys, I am stumped and need some help.

Little background: Have only brewed extract kits to-date. Recently built a keezer and started kegging 4 batches ago. Also have a separate freezer used as temp controller for fermenting. Have used the same buckets, carboys, kettle, and all other equipment since starting the hobby ~3 years ago (only 10 batches made so far). Clean with Oxyclean and rinse well. Sanitize with StarSan.

Since I began kegging, have had weird off-flavors in all my brews, some more than others. Mix between tasting metallic, alcohol-y, acidic. Not way over the top, but definitely noticeable. So much so that every beer tastes somewhat the same?

Recently brewed a Dry Dock Apricot Blonde clone from NB. 2 weeks primary, transferred to keg for 1.5 weeks (room temp), then moved to keezer and placed on CO2. The beer tasted great when I pulled a taste off the tap immediately after hooking up lines (without CO2). No hint of off-flavor. Set PSI to 12 (39deg) and "set and forget".

Couldnt resist tasting 3 days later, and I immediately got the weird 'alcohol' smell, as well as the metallic/acidic taste. Again, this was not present 3 days before.

I know, I know the beer is still "green". But, no way it could be over-carbed - was only at 12psi, still tasted flat, No foam whatsoever. No way it could be carbonic acid could it?

Thought that maybe it was the CO2 tank, as it was bought used on craigslist and I have used the same gas for all my batches. Yesterday I switched out the first tank with a different one that was filled by LHBS, bled off all gas in the kegs, and re-filled at 10-12psi with the new tank attached.

Came to garage today, pulled a sample of each of my brews and they taste COMPLETELY DIFFERENT. There is a very, very mild hint of the off-flavor in them all, but my Nut Brown actually tasted like a nut brown (not a watered down alcohol drink).

My question: Is it feasible that my first tank and/or CO2 is bad or contaminated?? And if so, is 1-2 days of being hooked up to a new tank enough time to really notice this much of a change? I am sure that not all of the first CO2 could be completely gone as I never truly 'de-gassed' the system.

 

[JonM]

Yes - in fact there was a thread not too long ago where the OP really investigated thoroughly and finally found out that he had bad gas (stop snickering ). But seriously, it can happen where something goes wrong with a CO2 refill. You might be on to something.

 

[collinsDPT]

It is the most bizarre thing.

 

[sabitu]

I ran into this same problem. I had a brown ale and a stout in my kegerator that had both been fully carbonated on the same CO2 tank and they tasted normal. This CO2 tank emptied so I switched it out for a spare tank that I always keep on hand. Both tanks were filled at the same place.

Well after a few days I tasted both beers and they had a weird off flavor that's hard to describe. They tasted bland with very little flavor and they had a bit of carbonation bite. My spare CO2 tank was at room temperature when I hooked it up to the kegs and my tank that emptied was cold since I keep it inside the kegerator. I can't say for sure but I maybe the fact that the new CO2 gas was at room temperature caused the problem?

Anyway, I took both kegs out of the kegerator and let them sit at room temperature for a couple weeks. I would bleed off the pressure several times a day until most of the CO2 was out of the beer. Once this was done I put them back in the kegerator and hooked them up to the same CO2 tank that caused the problem. After re-carbonating they taste perfectly normal! So in my case I know the CO2 isn't bad since I used the same tank, it's just frustrating that I can't find a definite cause.

Maybe sometimes when a tank is filled there is a little oxygen that comes out when the tank is first opened? This could cause the off flavor but I'm not sure if this is possible.