I'm in a similar situation to the OP in this thread. I think I under-pitched my yeast. Can you help me figure out if that's the case?

Here's the recipe I followed. I didn't measure the OG before I threw it in the fermenter and pitched. I have had good luck with just popping the nutrient pack on my Wyeast starters at least 3 hours before pitching.

This time I forgot and didn't pop it until about 2 hours. It had started to swell, but not a lot.

I brewed Oct 26 in the evening. Oct 27 the foam did (I think) turn into a krausen. I do have sediment on the bottom. I did see a lot of tiny particle activity when I looked close. I did not see any bubbles out of the airlock. I checked my lid (I'm in a Fermonster) and it was tight. I check the seal around the stopper and it was fine.

On Oct 28, I read up and decided I needed to check the gravity. It was 1.040. This beer is supposed to start at 1.070 and go to 1.015.

Here's my theory. Check me. It's on it's way from 1.070 to 1.015. It's fermenting. I had a leak in the o-ring under the lid that I couldn't see, so the excess air was going out of that instead of through the airlock. I just need to hold tight and I'll have beer.

I just don't understand why I haven't seen the airlock activity at all. I haven't experienced that before and this is my 9th batch of beer. Thanks.

  • 1
    As an aside: The recipe looks like it was written in the 1990s. Consider moving the boil hops to the end of the boil, and whirlpool for 10-20 minutes after flameout for maximum flavor impact. A typical American IPA will have 4-5 oz late hops in a 5-gallon batch -- this recipe has about half that much, not enough for a great example of the style. Unless you don't want it overly hoppy. Ultimately, brew what you enjoy, of course!
    – dmtaylor
    Commented Oct 29, 2019 at 0:38
  • Thanks for adding the aside, @dmtaylor. I'm still so new that I follow the recipes pretty much to the letter. Notes like yours will help me experiment and discover what I like over time. I've made this recipe once before and absolutely loved it, but I didn't realize that it appeared light on hops, so I'm excited to try more and see. Commented Oct 29, 2019 at 15:45

1 Answer 1


Yes, you have a fermentation happening. As you yourself admit, the leakage out of the lid is the reason why the airlock doesn't seem to be working. But not to worry, everything will turn out fine. You underpitched a little bit, but since you saw signs of fermentation within a day, everything should be good anyway. Next time pop the pack earlier and consider making a yeast starter if it doesn't swell very fast within say 8-12 hours. Just 2-3 hours is not enough to know if it is healthy yeast. Give it more time. A day or two before is great if you can do it.

  • Just want to add that you should make sure the temperature is consistent during fermentation. If the temperature drops, it can slow down fermentation...
    – Philippe
    Commented Oct 29, 2019 at 13:20

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.