I did 18 liters of dark strong Ale beer

  • A first fermentation was during a period of a week in a bottle glass of 20 liters.

  • A second fermentation was inside little bottles of 355 mL each one
    during 3 weeks.

To get $CO_2$ I added 6 gr per liter of sugar, but when I opened each beer I discovered a considerable amount of $CO_2$.

I do not know what happened or what was the reason of that phenomena. That recipe I used it in the past and nothing like that happened.

Could you please deduce the step when I got that pollution?

  • By "polluted" I believe cMinor means "over-carbonated." Nov 8 '12 at 2:23

What was the starting gravity and ending gravity? Did you confirm that fermentation had completed before bottling?

6g/litre should give around 2.5 volumes of CO2, depending on the final temperature of the beer, according to this tool. That's about right for a Belgian ale.

I think your problem is most likely that you bottled the beer before it had finished fermenting. One week is a very short time for fermentation, especially if the beer had a high starting gravity, as I expect it did since it's a "dark strong ale".

Next time, take gravity readings on three consecutive days. If the gravity does not drop over that period, you can consider the fermentation done and bottle. Though many beers show an improvement in flavor if you leave them on the yeast for a few weeks. Generally I leave my beers alone for three weeks before thinking about bottling.

  • But leaving alone the beer for 3 weeks could get you esters that do not belong to a particular beer style, is that correct?
    – edgarmtze
    Nov 1 '12 at 23:56
  • I don't think that's correct. Esters are formed in the first few days of fermentation, due to low pitching volume or higher than optimum temperatures. In fact, post-fermentation the yeast will clean-up some off-flavors. Mostly higher-alcohols and acetaldehyde, but maybe esters as well. Besides, if this is a Belgian ale we're talking about, esters do belong. Many people will ferment Belgian ales at artificially high temperatures to induce ester formation. Nov 2 '12 at 0:04
  • 1
    @cMinor, leaving a beer for 3 weeks will make for a cleaner beer, actually. The yeast need time to clean up their byproducts after fermentation is done. You shouldn't ever bottle a beer that's less than 2-3 weeks old.
    – Graham
    Nov 2 '12 at 12:51

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