Yeast Pitched But No Fermentation? What to Check
I Pitched My Yeast Two Days Ago – Why Is Nothing Happening?
You brewed your beer, pitched the yeast and fitted the airlock. Two days later there's still no bubbling.
Don't panic and don't immediately add another packet of yeast.
An airlock is useful but it is not a fermentation meter. Before deciding your yeast has failed, there are a few simple things to check.
1. Check the Fermenter Seal
One of the most common reasons for an airlock that doesn't bubble is simply a small leak around the fermenter lid, seal or airlock grommet.
Fermentation may be progressing perfectly well but instead of the CO₂ escaping through the airlock, it's finding another way out.
Look for other signs of fermentation such as foam or krausen on top of the beer, condensation inside the fermenter or a change in gravity.
No bubbles doesn't necessarily mean no fermentation.
2. Check the Gravity
This is the best way to find out what's really happening.
Take a hydrometer reading and compare it with your Original Gravity (OG).
If your beer started at 1.045 and is now sitting at 1.025, fermentation is definitely underway — regardless of what the airlock is doing.
If the gravity hasn't moved after around 48 hours, it's time to investigate further.
Brewer's rule: Trust your hydrometer before your airlock.
3. Check the Temperature
Yeast works best within its recommended fermentation temperature range. If the wort is too cold, fermentation can become very slow or the yeast may become dormant.
Different yeast strains have different requirements so check the temperature range printed on the yeast packet or manufacturer's instructions rather than assuming every yeast behaves the same way.
Also remember that the temperature of the beer itself matters, not simply the temperature of the room.
If it's too cold, warm the fermenter gradually into the yeast's recommended range. Don't suddenly expose it to excessive heat.
4. Was the Yeast Pitched Too Hot?
This is the opposite problem and potentially a more serious one.
If yeast is pitched into wort that's far too hot, you can damage or kill enough cells to prevent a healthy fermentation.
Always check your wort temperature before pitching the yeast.
If you're using dry yeast, follow the manufacturer's instructions. Many modern brewing yeasts can be sprinkled directly onto the wort while others may have specific rehydration recommendations.
5. Is the Yeast Old?
Yeast is a living microorganism and its viability gradually declines with age, particularly if it has been stored badly.
An older packet doesn't automatically mean the yeast is useless but age, storage temperature and handling all matter.
Check the best-before date and think about how the yeast has been stored. Keeping unopened yeast according to the manufacturer's storage instructions gives it the best chance of remaining healthy.
If you're using yeast that's well past its date, expect fermentation to potentially start more slowly.
6. Give It a Little Time
Not every fermentation takes off dramatically within a few hours.
Yeast needs time to adapt, reproduce and begin actively fermenting the sugars in your wort. Depending on the yeast, wort, pitching rate and temperature, visible signs may take longer than expected.
If you're still within roughly the first 24–48 hours, the temperature is correct and everything else looks normal, sometimes the best thing to do is simply leave the fermenter closed and give the yeast time to work.
Constantly opening the fermenter to check it can introduce unnecessary oxygen and contamination.
When Should You Add More Yeast?
Don't add another packet simply because the airlock isn't bubbling.
First:
Check the seal • Check the gravity • Check the fermentation temperature • Check the yeast
If the gravity hasn't changed after about 48 hours, the wort is at the correct temperature and you're confident the original yeast is not viable, then pitching a fresh, healthy packet of suitable brewing yeast may be the sensible next step.
What About Sanitisation?
Good cleaning and sanitising are essential but poor sanitisation doesn't normally explain a completely inactive fermentation.
Its main risk is allowing unwanted microorganisms into your wort which can cause off-flavours, sourness or spoilage.
Clean everything that touches your beer after the boil and sanitise it properly. Follow the sanitiser's recommended dilution and contact time.
Clean equipment first. Sanitise second.
Brewer's Tip
Before pitching your yeast, write down three things:
Original Gravity • Wort Temperature • Yeast Used
Those three pieces of information make troubleshooting a slow fermentation much easier.
Final Pour
Two days without bubbles doesn't necessarily mean your brew has failed.
Quite often the beer is fermenting and the fermenter simply isn't perfectly airtight.
Check the gravity first, then temperature and yeast condition before doing anything drastic.
Don't judge fermentation by bubbles alone — let the hydrometer tell you what's happening.