Don't Despair, There's Repair: Fixing Stuck Beer Fermentations

Homebrew fermentation stuck? We give you step-by-step troubleshooting guidance to help get you back on track.


Mat Stuckey

9/1/20232 min read

Don't Despair, There's Repair: Fixing Stuck Beer Fermentations

Uh oh, is your beer fermentation stuck? Those anxious airlock bubbles have slowed to a halt before your final gravity. While frustrating, a stuck ferment is not the end of your brew! With a methodical troubleshooting process, you can get your fermentation re-started and back on track.

First off - don't panic! Stalled fermentations happen to every homebrewer eventually. Stay calm and work the problem. With a little brewer's problem-solving, you'll be back to brewing in no time.

Fixing Stuck Fermentation

Fixing stuck beer fermentations involves diagnosing the stall signs, then methodically troubleshooting with temperature adjustments, yeast viability checks, wort aeration, and, if necessary, repitching fresh yeast.

Diagnosing a Stuck Fermentation

Before taking action, confirm your fermentation is actually stuck by:

Taking a hydrometer reading - Has gravity changed in 48 hours? Stable gravity indicates a stick.

Inspecting the krausen - Has the thick foam fallen? Another sign fermentation is slowing.

Checking the airlock - Bubbles slowed from active fermentation? Likely a stalled brew.

Tasting a sample - Is the beer overly sweet? That's the unused sugars calling!

Once confident your ferment is stalled, it's time to troubleshoot the root cause and get it restarted.

Step-By-Step Troubleshooting for Stuck Fermentations

Walk through these methodical troubleshooting steps:

Step 1 - Temperature Check

  • Is the beer too cold? Below 60°F yeast activity slows dramatically.

  • Gently warm the fermenter to 65-72°F range if too chilly.

Step 2 - Verify Yeast Viability

  • If fermentation was vigorous then slowed, yeast is likely still viable.

  • Take a small sample and microscope check for active yeast cells.

Step 3 - Check Yeast Flocculation

  • Has yeast dropped out early due to cold temps or high flocculation?

  • Swirl fermenter to rouse settled yeast back into suspension.

Step 4 - Rehydrate Dry Yeast

  • Make a starter by rehydrating a pack of dry yeast.

  • Once active, add the fresh yeast to jump-start fermentation.

Step 5 - Aerate Wort

  • Use an aeration wand or splash racking to introduce oxygen.

  • Yeast requires oxygen to remain active during fermentation.

Step 6 - Add Yeast Nutrients

  • Replenish necessary nutrients like nitrogen, zinc, and vitamins.

  • Consider a commercial yeast energiser product.

Step 7 - Repitch New Yeast

  • If above steps fail, pitch a fresh batch of yeast.

  • Make a large starter or double the cell quantity.

With persistent troubleshooting, you can rescue your beer from a stuck ferment! And take good notes so you can avoid the same problem next batch.

Preventing Stuck Fermentations

While not always avoidable, you can reduce the risk of stuck ferments by:

Pitching adequate yeast - Underpitching stresses yeast leading to early stalling.

Providing yeast nutrients - Replenishes zinc, nitrogen and other necessities.

Oxygenating wort - Allows healthy reproduction during exponential growth.

Controlling fermentation temperature - Cool ferments below 60°F risk slowing.

Using low flocculating yeast strains - Won't settle out prematurely.

Avoiding drastic temperature swings - Stability keeps yeast active and healthy.


Stuck fermentations can be a homebrewer's headache, but understanding the signs and having a systematic approach can be the remedy.

Remember, yeast is a living organism, and by understanding its needs and behaviour, you can nurture it back to activity. Your next perfect brew is just a few troubleshooting steps away.

So, take a deep breath, retrace your steps, and get that brew bubbling again!