• Bubbler Airlock with Red Cap
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Handcraft Supplies

Bubbler Airlock with Red Cap

Bubbler Airlock with Red Cap

£1.49
£1.49
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The classic S-shaped bubbler airlock with a red cap - fit it to your fermenter and you can see at a glance when fermentation is under way.

What it does

An airlock (also called a fermentation lock or trap) fits into a grommet in a fermenter lid or a bored rubber or cork bung. It lets CO2 escape during fermentation while keeping air and airborne contaminants away from your brew.

Features

  • Traditional S-shaped bubbler design
  • Red cap to keep dust and insects out
  • Fits standard grommets and bored bungs or corks
  • Supplier code: B-7127

How to use

Half-fill the airlock with water or sanitiser solution and push it into the grommet or bung. Once the yeast gets going, bubbles pass through the water - a handy sign your brew is fermenting.

Who it's for

Everyone who ferments beer, wine or cider. Cheap enough to keep a spare for each fermenter and demijohn.

Complete the set

Frequently Asked Questions
What do I fill the airlock with?
Fill to the fill line (roughly halfway) with either clean tap water or a weak sterilising solution. The liquid creates a one-way seal — CO2 from fermentation pushes through the liquid and escapes, but air cannot get back in. Using sterilising solution rather than plain water reduces the small risk of contamination if liquid is accidentally sucked back.
My airlock has stopped bubbling — is fermentation finished?
Not necessarily. Airlock activity slows significantly in the final days of fermentation and can stop while fermentation is still slowly completing. Never rely solely on airlock activity to judge when fermentation is done — always confirm with a hydrometer. Two identical readings 24 hours apart is the reliable test.
The liquid in my airlock got sucked into the fermenter — is my beer ruined?
Usually not. A small amount of sterilising solution or water being pulled into the beer during a sudden temperature drop is unlikely to cause a problem if the airlock was filled with sterilising solution. Taste the beer at the end of fermentation — if it seems off, investigate further, but in most cases it will be fine.
How many airlocks do I need?
One per fermentation vessel. If you run multiple batches simultaneously, you'll need one airlock for each. They're inexpensive, so it's worth having a few spares — they're easy to lose or break.
My airlock is leaking around the bung — what should I do?
The bung may not be seated properly or may have hardened and lost its seal. Press the bung firmly into the lid hole — it should fit snugly with no gaps. If the bung is cracked or hardened, replace it. A leaking seal allows oxygen into the fermenter which can cause oxidation and infection.