I was trying my first all grain brew yesterday when I realized that the beer was almost flat, which is weird because they spent about a week inside the bottle. It's a belgian golden ale and I've added about 10ml of a primming solution of 80g of sugar diluted in about 450ml of water (used an online calculator) for 33 cl bottles. What exactly has gone wrong? Was the yeast already dead at bottling or there wasn't enough sugar?

3 Answers 3


A week might not be long enough (especially if your yeast is particularly beleaguered, which would depend mostly on what the ABV of the finished beer is and how long it's been since fermentation).

Also, make sure your bottles are in a warm enough area (~70 °F is ideal for bottle-conditioning). Lower than this and it can definitely take several weeks, even with healthy yeast. I'd let it go a week or two longer and then if you don't see improvement, start to worry something went horribly wrong.

RE-editing: That might actually not be enough sugar. 10 ml of that solution would contain 1.5g. sugar (10g x [80g / 530g]). Using this calculator, at a beer temp. of 68 (a fair assumption), 1.5g sugar per 33cl (or 0.087 gal.) bottle would yield ~2.1-2.2 volumes of CO2, depending on what kind of sugar you use. Not super low, but also not super high either. I'd still wait and see if it turns around.

  • There was no airlock bubbling (which I know is hardly a good yeast activity measurement) on the last days on the fermenter. Sadly I did not measure original or final gravity. Temperature might indeed be the issue as they are on a room at about 10ºC (50 F)
    – joaocandre
    Feb 9, 2015 at 13:48
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    10ºC is cold enough that an ale yeast will pretty much be dormant. No worries though, if you can move your bottles to a warmer place, the yeast should become active again and start carbonating (assuming it is healthy, of course). The low temperature itself should not cause the yeast any harm. Feb 9, 2015 at 14:08
  • I was indeed going for about 2.15 volumes of CO2, follwoing the reference values for Belgian Ales (1.9~2.4) (brewersfriend.com/beer-priming-calculator was the calculator I used).
    – joaocandre
    Feb 9, 2015 at 15:12
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    Yeah, 50 F is too cool for bottle conditioning. In addition to warming them up try inverting them a few times once they're warm to resuspend the yeast that's settled out. It should help them to get going again. Feb 9, 2015 at 15:15

I don't think you have anything to worry about yet. Most of my batches take around 2 weeks to get to a reasonable level of carbonation, and are usually fully carbonated in about 3 weeks. Take Papazian's advice - Don't worry, have a Homebrew!

I would comment on the amount of sugar, but I can't tell the size of your batch from your post, but the standard for a 5 gallon batch would be 3/4 of a cup.

EDIT: My advice at this point would be to move them to a warmer room (at LEAST 65 °F), and wait another 2 weeks. If your beer is still entirely flat, there might possibly be something wrong with the yeast. My guess though is that it will be slightly carbonated, but not as much as you'd like. You could leave as is, or if you decide you want it more fully carbonated, you could just completely start the carbonation process over with more priming sugar (use roughly ~120 or 130g total this time).

Naturally, if there is no carbonation at all after 2 more weeks, you could move the beer back to a bottling bucket and re-pitch some more yeast along with the new priming sugar.

Good luck with whatever you choose. Let us know how it turns out!

  • It's a 15L batch. My concern came from my previous batch carbonated quite a lot on the first week. It was not all grain though, it was a kit.
    – joaocandre
    Feb 9, 2015 at 13:46
  • ahh. Well we're definitely on different measuring systems, but if the calculator I used is correct, 80 grams of sugar is equal to about 0.34 cups of sugar. If that's correct, then I'd say you used about half of the priming sugar that you should have. Either way, looking at your comment on Franklin's answer, I'd say the temperature is probably a bigger factor. Feb 9, 2015 at 14:05
  • and to comment on the all grain piece - that shouldn't affect the carbonation. With all grain, one of the ways it can go wrong is if you don't do the mashing properly and don't have enough fermentable sugars in the wort. But that should only affect fermentation and not the bottle conditioning. Feb 9, 2015 at 14:13
  • I was going for 2.15 volumes of CO2 - the reference values for Belgian Ales would be 1.9-2.4. I honestly can't comment on that because I have no practical experience regarding this Ale.
    – joaocandre
    Feb 9, 2015 at 15:14
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    My opinion (and it is only just that) is that over-carbonating a little bit is always a good idea, because you can always get rid of unwanted carbonation easily by pouring more vigorously, etc., but you can never add carbonation at the last minute (if you're doing it all naturally). Feb 9, 2015 at 16:53

I expereienced once an issue with my bottle caps. The caps were not tight, and all the carbon dioxide leaked out, laving a flat beer. Could that be the case with you?

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