I recently brewed a Schneider Aventus clone and the end result was a flat beer. I missed a step in the instructions to add a fresh dose of yeast a few days before bottling so I'm assuming that this is the result of sluggish yeast. I still have a gallon in secondary that I was aging on oak chips so I ordered a more yeast to add to that.

My question is can I pop the caps of the flat beers and add a small amount of yeast to each one and recap them? Is this a viable route to take or are the flat beers destined for the drain?

Edit: If I remember correctly I primed with 1/4 cup DME for a one gallon batch and 3/4 cup DME for a 3 gallon batch. I bottle conditioned/carbonated for a month in my basement which is a steady 68 degrees.

  • 2
    Can you tell us a little more about your procedure before resorting to drastic measures? How much sugar did you use at bottling for how much beer? What temperature were the bottles stored at? How long have they been conditioning at that temperature?
    – JoeFish
    Commented Nov 28, 2011 at 16:48
  • added some more details
    – awithrow
    Commented Nov 28, 2011 at 17:39
  • 1
    Thanks! Seems like an appropriate amount of DME for the style, and you gave it a good amount of time at a reasonable temp. Actually, you say 1/4 cup - at about 6oz / cup, that's only 1.5oz of DME. The calculators I've found suggest 2.75-3.6oz/gallon for the 3.7-4.7 volumes CO2 recommended in a Weizen. You may just need more fermentables in there, not more yeast.
    – JoeFish
    Commented Nov 28, 2011 at 18:08
  • 1
    Don't dump it, use it to make a sour and/or blend it with something else. Commented Dec 2, 2011 at 2:30
  • 1
    [hit enter too early]... If you try blending I would try it first with a small batch first. The beer in the bottles will keep for a while so you have time. The trick would be timing as you’ll still have all the existing concerns, oxygenation, infections etc . The best time to do it would be during fermentation, maybe towards the end of the primary stage. I haven’t tried this but the benefit of being a homebrewer is you can experiment as you don’t have MBA types breathing down your neck about cost. Commented Dec 5, 2011 at 17:46

4 Answers 4


I had a similar issue with an Imperial IPA I made this past summer. It was high gravity and was not carbonating in the bottles. I had waited some time for it to carb up and it just wasn't doing it, practically completely flat. I believe the yeast was spent as well. I ended up uncapping the bottles adding a few grains of dry yeast to the bottles and recapping. I took great measures to be as sanitary as possible. In the end this worked, the bottles carbed. However despite my best efforts to keep everything as sanitary as possible I did get visible infection in a handful of bottles. it wasn't serious and didn't alter the flavor too much for those affected, but it did occur. That being said it did work for the majority of my bottles. You have to weigh whether this is worth it or not for your brew. Link to my post from this summer


You could try putting dry ice in each bottle. Dry ice is just frozen CO2. Buy a block and break it up into smaller enough pieces to get them into the bottle and recap. The dry ice will melt and return to a gas and carbonate your beer. Might be a little difficult to calculate the amount to put in but I'm sure the formulas are out there.

Don’t throw out your beer there is always something you can do with it.

  • "The dry ice will melt and return to a gas" --- This process is not melting, it's sublimation.
    – BeerSensor
    Commented Jan 13, 2012 at 3:02

I wouldn't; you risk making bottle-bombs. I don't think there's anything you could really do here. If you had a kegging system, you could try dumping them all in there, forcing carbonation, and drinking relatively quickly. It's too much exposure to open air and unsanitized surfaces for my liking, but it'd be worth a try.

  • You'd be able to work out how much to add. Calculate how much co2 is in a 1/2 inch cube and go from there. Plus if you had a way to keep the dry ice frozen you could experiment with a couple of bottles. Commented Dec 5, 2011 at 17:30
  • I have a munich dunkel that didn't carbonate. Super pissed as we did a decoction (first one) and it took forever. Am going to try this today. Local homebrew store guy here in SF told me about this, works for him. Commented Dec 5, 2011 at 17:32

It might work, but you run the risk of infection and even more oxygen in the package. If the alternative is dumping them, I'd say it's worth a shot.

  • The beer is pretty hardy at that stage, very little Oxygen plus the alcohol. I think you'd have to try pretty hard to get an infection. Commented Dec 5, 2011 at 17:23
  • Pediococcus and other LAB's prefer anaerobic environments.
    – BeerSensor
    Commented Jan 13, 2012 at 3:04

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.