My cider has been fermenting for five weeks. I still notice streams of tiny bubbles when I hold a flashlight to the glass fermenter.

I threw the cider together on a whim before work one day in mid-November.

Recipe details:

  • made the cider on or around around November 18 - it is simply frozen apple juice concentrate, with no preservatives, diluted to 1.055; I am hoping for a tart, apple-y, bottle-carbonated cider that I will slightly backsweeten with xylitol or other artificial sweetener;
  • followed proper sanitation procedures;
  • Pitched with 5.1 grams of Mangrove Jack M-02 cider yeast, properly rehydrated, at 70°F
  • has been fermenting at cellar temp (started at 67°F and dropped over last week to 62°F)
  • began fermenting vigorously at around 48 hours, vigorous fermentation slowed down after no more than eight hours, and I have been seeing tiny bubbles rising continuously since then;
  • There is a firm white yeast cake - about 1/3 inch deep;
  • I don't know the current gravity, and don't intend to take a gravity reading if I can avoid it due to this being a small batch;
  • I have never used this yeast before.

Edit: Specific gravity seems stuck at 5.6°Bx, so I posted another question.

2 Answers 2


Bubbles really tell you nothing. It's possible for fermentation to be finished, yet see bubbles rising due to the release of CO2 dissolved into solution during fermentation.

  • All right, I guess I will have to take a gravity reading. Any tips on pulling a sample without introducing too much oxygen into the fermenter? I have a beer thief and refractometer, but no way to purge with CO2. Dec 27, 2013 at 19:59
  • O2 is not a big concern. I wouldn't worry about it.
    – Denny Conn
    Dec 27, 2013 at 20:00
  • 1
    If you use some kind of pipette for taking a refractometer sample, and you sanitize first in boiling water or no-rinse sanitizer, you'd be best advised to suck up a little bit of cider, throw that out, suck up another sample, and drip that on your refractometer. Otherwise you can dilute your sample with the tiny bit of water/sanitizer on the pipette; when your sample is tiny, even a very small amount of 'water' will screw up your reading.
    – Dale
    Dec 28, 2013 at 23:17
  • 1
    And if you use a refractometer, be sure to use a correction chart to get an accurate reading. The alcohol present during and after fermentation can throw a refractometer off.
    – Denny Conn
    Dec 29, 2013 at 17:20

Sad to say, but without gravity readings we know nothing. Bubbles are strongly correlated to active fermentation but no guarantee that it is of significant measure.

That said, some buddies of mine who do cider give ridiculous cycles, up to and past five months IIRC.

  • True. It's not uncommon for my ciders to spend 2-3+ months in primary and several more in secondary.
    – Denny Conn
    Dec 27, 2013 at 20:02

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