SCOBY FAQ
Is a SCOBY a mushroom?
No, a kombucha SCOBY is not a mushroom or fungus. SCOBY stands for Symbiotic Culture of Bacteria and Yeast. It’s sometimes nicknamed a “mushroom” because it looks like one, but that’s a misnomer. A SCOBY is actually a cellulose-based biofilm formed by the fermentation process.
What are those brown, gloopy things in my kombucha?
Brown, gloopy thing = yeast
Not a fan of yeast? Strain it out! Use a clean fine mesh strainer to filter out those ‘gloopies’ in your bottling process.
Those brown, stringy or gloopy bits in your kombucha are just yeast strands—totally normal and a sign that fermentation is happening. Too much yeast can affect taste. Common causes include:
Not a fan of yeast? Strain it out! Use a clean fine mesh strainer to filter out those ‘gloopies’ in your bottling process.
Those brown, stringy or gloopy bits in your kombucha are just yeast strands—totally normal and a sign that fermentation is happening. Too much yeast can affect taste. Common causes include:
- Brewing too warm (ideal is 68-78°F)
- Using raw or mineral-rich sugar instead of plain cane sugar
- Using only bottom-of-the-jar starter liquid (it’s yeastier)
What happens if my SCOBY gets too thick?
If your SCOBY is more than 3 inches thick, it’s time for a “SCOBY haircut”! Keeping your SCOBY trimmed helps ensure balanced fermentation and prevents overly fast brews. Most people trim every 2-5 months. Always use clean hands and tools, and peel or cut from the bottom up.
What would make mold grow on my SCOBY?
Mold is one of the few real deal-breakers when it comes to brewing kombucha. While stringy yeast, odd textures, and even some unusual smells are totally normal, mold is not.
Mold looks dry and fuzzy and is typically white, green, blue, gray, or black. It grows on the surface of the SCOBY or liquid. If you were to touch it (which we don’t recommend), a powdery residue might come off on your finger.
Bottom line: If you see mold, you must throw away the entire batch SCOBY and liquid. Mold can release toxins that may contaminate the whole brew, even if you remove the visible spots.
Common reasons your SCOBY grew mold:
Mold is a sign that your brew isn’t acidic or active enough to fight off outside contaminants. Here are the most common culprits:
1. Weak or missing starter tea
Starter tea (already brewed kombucha) helps quickly lower the pH of your sweet tea mixture, creating a safe, acidic environment. Without it, mold has an easier time taking hold.
Tip: Always use at least 1 cup of strong, unflavored starter tea per gallon. The top of the previous batch is best, as the bottom tends to be yeast-heavy
2. Adding hot tea too soon
If you pour your sweet tea into the jar before it has cooled to room temperature, it can kill the beneficial microbes in your starter tea and SCOBY.
Tip: Let the tea cool to room temperature (around 75°F) before combining it with your SCOBY and starter liquid.
3. Using weak kombucha as starter liquid
If your kombucha hasn't fermented long enough, it won't be acidic enough to act as effective starter tea.
Tip: Make sure your kombucha has that tangy, vinegar-like flavor before using it as starter—this usually takes 7 to 14 days, depending on temperature.
4. Brewing in too cold an environment
Temperatures below 68°F can slow or stop the activity of fermentation, giving mold an opportunity to grow.
Tip: Move your brewing jar to a warmer spot—such as a high shelf or cupboard—or use a kombucha heating wrap to keep it within the ideal range of 68–78°F.
5. Using flavored teas
Flavored teas and teas with essential oils (like Earl Grey) can interfere with fermentation or harm the SCOBY.
Tip: Use only plain black, green, oolong, or white teas for primary fermentation. Save herbal teas and flavorings for your second fermentation.
6. Using the wrong sweetener
Raw sugars like honey, coconut sugar, or agave may seem healthier, but they can disrupt fermentation or cause the brew to become unbalanced.
Tip: Stick to granulated white sugar or organic cane sugar in your primary fermentation.
7. Contaminated brewing environment
Mold spores in your kitchen—especially near compost, trash, or ripening produce—can float into your brew and settle on your SCOBY.
Tip: Brew kombucha away from window sills, fruit bowls, trash cans, or houseplants. If mold continues to appear, try moving your jar to a different part of your home.
Mold looks dry and fuzzy and is typically white, green, blue, gray, or black. It grows on the surface of the SCOBY or liquid. If you were to touch it (which we don’t recommend), a powdery residue might come off on your finger.
Bottom line: If you see mold, you must throw away the entire batch SCOBY and liquid. Mold can release toxins that may contaminate the whole brew, even if you remove the visible spots.
Common reasons your SCOBY grew mold:
Mold is a sign that your brew isn’t acidic or active enough to fight off outside contaminants. Here are the most common culprits:
1. Weak or missing starter tea
Starter tea (already brewed kombucha) helps quickly lower the pH of your sweet tea mixture, creating a safe, acidic environment. Without it, mold has an easier time taking hold.
Tip: Always use at least 1 cup of strong, unflavored starter tea per gallon. The top of the previous batch is best, as the bottom tends to be yeast-heavy
2. Adding hot tea too soon
If you pour your sweet tea into the jar before it has cooled to room temperature, it can kill the beneficial microbes in your starter tea and SCOBY.
Tip: Let the tea cool to room temperature (around 75°F) before combining it with your SCOBY and starter liquid.
3. Using weak kombucha as starter liquid
If your kombucha hasn't fermented long enough, it won't be acidic enough to act as effective starter tea.
Tip: Make sure your kombucha has that tangy, vinegar-like flavor before using it as starter—this usually takes 7 to 14 days, depending on temperature.
4. Brewing in too cold an environment
Temperatures below 68°F can slow or stop the activity of fermentation, giving mold an opportunity to grow.
Tip: Move your brewing jar to a warmer spot—such as a high shelf or cupboard—or use a kombucha heating wrap to keep it within the ideal range of 68–78°F.
5. Using flavored teas
Flavored teas and teas with essential oils (like Earl Grey) can interfere with fermentation or harm the SCOBY.
Tip: Use only plain black, green, oolong, or white teas for primary fermentation. Save herbal teas and flavorings for your second fermentation.
6. Using the wrong sweetener
Raw sugars like honey, coconut sugar, or agave may seem healthier, but they can disrupt fermentation or cause the brew to become unbalanced.
Tip: Stick to granulated white sugar or organic cane sugar in your primary fermentation.
7. Contaminated brewing environment
Mold spores in your kitchen—especially near compost, trash, or ripening produce—can float into your brew and settle on your SCOBY.
Tip: Brew kombucha away from window sills, fruit bowls, trash cans, or houseplants. If mold continues to appear, try moving your jar to a different part of your home.
Can I put my SCOBY in the fridge?
I don’t recommend storing your SCOBY in the fridge. Cold temperatures slow down or stop the activity of the yeast and bacteria, making them less effective once you start brewing again. This can lead to an imbalanced fermentation and increase the risk of mold.
If you need to take a break from brewing, check out the “How to take a break from brewing kombucha” section for safe long-term storage tips.
If you need to take a break from brewing, check out the “How to take a break from brewing kombucha” section for safe long-term storage tips.
My SCOBY sank to the bottom of my brewing vessel - does that mean it’s dead?
Not at all. Healthy SCOBYs can float, sink, or hover somewhere in between—it’s all normal. When you first add a SCOBY to a fresh batch of sweet tea, it may sink to the bottom, but that doesn’t affect its ability to ferment.
A new SCOBY layer will begin forming on the surface of your brew within a few days. Sometimes the original SCOBY can also shift positions mid-brew, especially if there's a sudden change in temperature.
A new SCOBY layer will begin forming on the surface of your brew within a few days. Sometimes the original SCOBY can also shift positions mid-brew, especially if there's a sudden change in temperature.
How do I take a break from brewing kombucha?
If you need to pause your kombucha brewing, you can safely store your SCOBY at room temperature for several weeks. Here's how:
To feed your SCOBY:
It’s also a good idea to check in weekly to make sure the liquid hasn’t evaporated too much. If it has, top it off with additional sweet tea.
This method is sometimes called making a “SCOBY hotel” - a resting place to keep your culture alive between batches.
- Leave your SCOBY in its brewing jar (countertop, cupboard, or pantry is fine—just avoid the fridge).
- Make sure the jar is at least halfway full with already brewed kombucha (this is your starter liquid). This keeps the environment acidic and protective.
- Cover the jar with a breathable cloth and secure it with a rubber band or jar ring. This keeps out dust and fruit flies while still allowing airflow.
- Store the jar for up to 4-8 weeks. After that, your SCOBY will need to be “fed.”
To feed your SCOBY:
- Brew 1 cup of strong black tea and dissolve 1/3 cup sugar in it.
- Let it cool completely to room temperature.
- Add the sweet tea to your SCOBY jar.
It’s also a good idea to check in weekly to make sure the liquid hasn’t evaporated too much. If it has, top it off with additional sweet tea.
This method is sometimes called making a “SCOBY hotel” - a resting place to keep your culture alive between batches.
Check out some healthy, yet funky looking SCOBY's in KTTP's Healthy SCOBY Gallery