A leaky SCOBY: problem or normal behaviour?

You start a new batch of kombucha.
You carefully place your SCOBY on the surface of the sweet tea. It floats for a moment, then… gloups. It sinks to the bottom of the jar or lies askew, like a pancake that hasn’t decided to stay on top.

At that point, a lot of questions come to mind:

• Is my SCOBY dead?
• Will fermentation still work?
• Did I miss anything in the preparation?

This is a very common worry, especially at first. We often imagine that a « healthy » SCOBY should float to the surface like a buoy. In reality, this is not an obligation at all. A SCOBY can :

• float
• sink
• stand halfway at an angle
• go up a little later

and stay perfectly healthy.

In most cases, a leaking SCOBY is normal behaviour that does not call fermentation into question. Especially if you’re working with a robust culture like a SCOBY Natural Probio, the most important thing is not the position of the old disc, but the ability of the new batch to create a baby SCOBY on the surface.

In this article, we will :

• explain why a SCOBY sometimes floats and sometimes sinks
• see in which cases a SCOBY at the bottom is totally normal
• distinguish between reassuring and worrying signs
• show you how to react (or not react) when it sinks
• give you some best practices for handling your SCOBY Natural Probio without stress

Understanding what a SCOBY physically is

To understand why it sinks or floats, you first need to know what it’s made of.

A cellulose biofilm soaked in liquid

A SCOBY of kombucha is above all :

• a cellulose matrix (like a gelatinous pancake)
• produced by the bacteria present in the culture
• in which yeasts and other bacteria settle

This biofilm is soaked in liquid:

• initially, the kombucha in which he grew up
• then, when transferred, the new sweet tea

Depending on its density, thickness and internal structure, it can :

• be slightly less dense than the liquid and float
• be denser and flow
• stay between two waters, stuck to the wall, etc.

The SCOBY is not a « boat » designed to float permanently. It behaves like a living object soaked in water, subject to gravity and the movements of the liquid.

A living organism, not a fixed object

The SCOBY is not frozen in time:

• it is loaded with liquid
• it can be partially emptied depending on handling
• it sometimes produces gas bubbles inside the biofilm
• its structure can change over the course of a batch

All these factors influence its buoyancy. So it’s normal that it doesn’t always behave the same way from one batch to the next, even if you use the same SCOBY Natural Probio.

What really happens when you launch a new batch

When you launch a new homemade kombucha, several things happen in the jar.

The initial SCOBY investment

You start with :

• prepare a sweet tea
• let the tea cool completely
• add a portion of very acidic kombucha (mother kombucha)
• place your SCOBY on the surface

At this point, two scenarios are most likely to occur.

1. The SCOBY floats to the top:
   • the surface of the disc coincides with the surface of the liquid
   • it can stay that way for a few hours or even several days
   • a new film sometimes begins to form on it
2. The SCOBY is sinking fast:
   • it is denser than the liquid
   • it slides down the wall or falls straight to the bottom
   • the surface of the liquid remains « bare » for the time being

In both cases, the culture of yeasts and bacteria is present. Whether the disc is at the top or the bottom, the micro-organisms it contains will :

• consume the sugar in tea
• produce alcohol and organic acids
• gradually acidify the environment

The birth of a new SCOBY on the surface

The key point is this: the SCOBY that really ferments the new batch isn’t necessarily the old record. What counts is the ability of the culture to form a new film on the surface of the jar.

Even if your SCOBY Natural Probio sinks to the bottom :

• the bacteria present in the liquid will rise
• a thin transparent film will form on the surface
• this film will gradually thicken
• after a few days, a new « baby SCOBY » becomes visible

It is this new surface SCOBY that is often best suited to the current batch. It forms exactly at the air/liquid interface, where certain acetic bacteria like to work.

In other words: a sinking SCOBY does not prevent the creation of a new SCOBY on the surface, which will take over.

Seven common reasons why a SCOBY sinks

There is no single explanation. Several factors can, individually or in combination, sink your SCOBY.

1. It is very soaked and denser than the liquid

With successive batches, a SCOBY :

• accumulates layers
• is loaded with liquid
• becomes heavier

If your jar contains a relatively light (less dense) tea, the SCOBY may simply be denser than the liquid. Gravity will do the rest: it will sink.

This is particularly common with an old, thick SCOBY.

2. It has been handled, cut or punctured

When you :

• cut a SCOBY in half
• tear it open and share it
• hold it with your fingers as you bend it
• pierce it with yeast bubbles

you modify its structure:

• air pockets are emptied
• the distribution of cash changes
• the load-bearing surface is reduced

As a result, he loses buoyancy and can sink more easily. This does not mean that he is in poor health, only that his physical condition has changed.

3. Kombucha is very acidic when transferred

If you transfer the SCOBY into a liquid :

• very acidic (lots of concentrated kombucha mother)
• a little sweet to start with

The density of the medium may be higher than that of conventional sweet tea. Depending on the ratio between the density of the SCOBY and that of the liquid, it may float differently – sometimes sinking when it was floating before, or vice versa.

4. Temperature causes densities to vary

Temperature affects :

• the density of the liquid
• viscosity
• the rate of formation of CO₂ and other gases

Very cold kombucha (or tea that is not completely at room temperature) may behave differently from well-tempered kombucha:

• SCOBY can sink at the start
• then raise the temperature a little as the jar warms up and bubbles form

This remains a mechanical phenomenon, not a health diagnosis.

5. It’s a young, very fine SCOBY

A very thin SCOBY baby:

• can roll up on itself
• stick to the wall
• move more easily through the liquid

If you are only using a very young SCOBY, it is normal for it to have unstable floating behaviour. It does not yet have a large surface area and sufficient thickness to remain spread out on the surface.

6. You’ve just checked him out of a hotel in SCOBY

In a hotel in SCOBY, the :

• overlap
• are filled with liquid
• sometimes take irregular shapes

When it’s time to put them back into a new cup of sweet tea, they can :

• withdraw
• stick together
• fall to the bottom en bloc

It doesn’t matter. The most important thing, once again, is that the microbial culture is active and that the medium is acidified with the mother kombucha.

7. A new SCOBY is formed, and the old one gives way

Sometimes the explanation is very simple:

• a new SCOBY baby begins to form on the surface
• the old disc is slowly coming off
• it finds itself underneath, then ends up sinking

This leaves you with :

• a new SCOBY firmly on the surface
• one or more old discs lower down or at the bottom

This behaviour indicates a dynamic culture rather than a problem.

What’s normal with a sinking SCOBY… and what you should be aware of

A SCOBY is nothing to worry about in itself. What matters are the other signs that accompany it.

When a sinking SCOBY is totally reassuring

Everything is normal if :

• the smell of the jar is pleasant: kombucha, cider, sweet vinegar, fermented tea
• the taste changes from day to day: from sweet to more acidic
• after a few days, a new film begins to form on the surface
• no mildew or foamy stains appear on the liquid

In this case :

• it doesn’t matter if your SCOBY Natural Probio is at the bottom of the sea.
• fermentation works
• the drink is transformed, the environment remains protected by acidity
• the new surface SCOBY becomes your best health indicator

When a leaky SCOBY could be a symptom of a problem

A leaky SCOBY can be associated with a worry if:

• after 7 to 10 days (at the correct room temperature), no acidity appears
• the drink remains very sweet, almost as it was at the start
• no new film forms on the surface
• the smell is strange: rotten egg, dustbin, damp mould
• you see fluffy coloured spots on the surface (mould)

In this case, the problem is not that it sinks, but that :

• fermentation is not taking place correctly
• or that the environment is contaminated

What you do then depends on what you observe:
sometimes you need to correct the fermentation conditions (temperature, sugar, kombucha mother), sometimes you need to throw it out and start again with a healthy SCOBY.

What to do if your SCOBY Natural Probio leaks

Most of the time, the best reaction… is to do nothing special. But there are a few things you can do to help.

1. Leave him alone for the first few days

After placing your SCOBY Natural Probio in the jar :

• if it sinks, don’t keep fishing it out
• don’t shake the jar every day to reposition it
• focus on the evolution of taste and smell

Leave for at least 4 to 5 days at the correct room temperature before drawing any conclusions.

2. Watch the surface, not just the bottom

Even if the SCOBY is at the bottom, observe:

• On the surface of the liquid: can you see a translucent film forming?
• Do small bubbles sometimes stick to the sides of the jar?

These are signs that fermentation is underway and that a new SCOBY is being born.

3. Taste regularly

From the fourth or fifth day:

• taste a teaspoon of liquid without shaking the jar
• note the evolution: a little less sugar, a hint of acidity, then an increasingly kombucha profile

If the transformation takes place, the fact that the SCOBY is at the bottom is not a problem.

4. Check the general conditions

If you’re really worried, start from the basics:

• Is the room warm enough (around 22-24°C)?
• did you add enough sugar to start with?
• did you add kombucha acid mother to your SCOBY Natural Probio?
• Is the jar covered with a breathable fabric rather than hermetically sealed?

Sometimes improving one of these points is enough to kick-start a timid fermentation.

Is it necessary to « reassemble » a sinking SCOBY?

Natural question: if my Scoby sinks, do I have to bring him to the surface with a spoon to « help » him?

In the vast majority of cases: no

Pull up the SCOBY :

• risk of tearing it
• introduces potential germs if your hands or utensils are not perfectly clean
• can interfere with the formation of the new film on the surface

As fermentation can be carried out with a SCOBY at the bottom, there’s no need to manipulate it just for aesthetic reasons.

Exception: a SCOBY stuck in an awkward position

In certain special cases :

• the SCOBY is folded in a strange way
• it sticks tightly to a very narrow edge
• it blocks part of the jar and prevents a new film from forming properly on the surface, for example

You can then :

• use clean hands or clean pliers
• gently reposition the SCOBY to release it
• however, avoid repeating the procedure every day

But these are rare situations. Most of the time, a sunken SCOBY does not interfere with the formation of the surface baby.

What a sinking SCOBY does NOT mean

It is useful to clear up a few common misconceptions.

« If it sinks, it’s dead ».

Not true.
A dead or badly damaged SCOBY can sink, but so can a live one. Position alone is not enough to draw a conclusion.

What counts in judging :

• the smell (pleasant vs. putrid)
• changes in taste (increased acidity)
• the formation of a new surface SCOBY

If all this is on track, life is here to stay, even if the old record rests at the bottom.

« If it floats, it’s in great shape ».

Not necessarily.
A SCOBY can float simply because it has :

• bubbles trapped in its structure
• momentarily low density

It’s nice to look at, but it’s not an automatic health diagnosis.
Once again, it’s the development of the kombucha itself that counts.

« A good SCOBY always floats

No.
Even an excellent, healthy and very active SCOBY Natural Probio can :

• float on a batch
• flow onto the next
• partially reassemble later

You have to accept that the position of the disc is a moving parameter.

Scooby in the background and real problems: how do you tell the difference?

To help you decide, here are some typical combinations.

Case 1: SCOBY on the bottom + acidifying drink + baby SCOBY on the surface

Verdict: everything’s fine.

• fermentation works
• the new SCOBY takes over
• you can continue to brew as normal

Keep the old disc if you like, but it’s the surface baby that will become the future champion of your batches.

Case 2: SCOBY at the bottom + drink that doesn’t change + no film at all

Verdict: stuck or very weak fermentation.

Here you need to look at :

• the temperature
• sugar
• the tea used
• the quantity of mother kombucha
• SCOBY’s state of health (smell, colour, texture)

Depending on what you find, you’ll need to :

• either correct the conditions (and sometimes reactivate the crop)
• or start again with a healthy SCOBY if the current strain is too weakened

Case 3: SCOBY at the bottom + suspicious smell + fluffy patches on the surface

Verdict: probable contamination.

The position of the SCOBY is secondary here. Mould (green, blue, black, white cottony patches) and rotten smells are clear signs:

• we don’t drink
• no attempt to « save » the batch
• throw everything away and clean the equipment

A new purchase of SCOBY Natural Probio or the use of a SCOBY from a healthy hotel will enable you to start again on a clean footing.

Best practices to reassure your SCOBY… and yourself

Even if a leaking SCOBY isn’t a tragedy, there are a few things you can do to limit your worries.

1. Start with a healthy, robust stock

When you’re just starting out, everything is easier with a quality SCOBY, suitable for sweet tea and supplied with a sufficiently acidic mother kombucha.

This is precisely the case with SCOBY Natural Probio:

• balanced culture of yeasts and bacteria
• well acidified starting medium
• clear instructions for first batches

The more reliable the strain, the more you can put little details like « floats » or « sinks » into perspective.

2. Stabilise conditions as far as possible

Micro-organisms like stability:

• moderate and fairly constant temperature
• consistent recipes (same type of tea, comparable proportions of sugar)
• jar covered in the same way (breathable, elastic fabric)

By controlling these parameters, you reduce the variables. If something changes, you can identify it more easily.

3. Observe over several days before drawing conclusions

A snapshot isn’t worth much. A SCOBY that sinks on Day 1 can be accompanied by :

• of a new film on the surface on day 5
• a kombucha that was already tangy on day 7

Rather than deciding after a few hours that « nothing works », give yourself a window of observation over a few days, tasting, smelling and looking at the surface.

4. Keeping a hotel in SCOBY as a safety net

With a well-maintained hotel in SCOBY:

• you have several spare disks
• you can test without fear
• if a batch goes wrong, you’ll leave immediately with another healthy SCOBY

Knowing that you have reserves changes everything psychologically: you observe with more curiosity, less fear.

In conclusion: a sinking SCOBY is not a shipwreck

Seeing your SCOBY of kombucha sink to the bottom of the jar for the first time can be disorientating. It’s easy to project the idea of failure onto this simple gesture: « it doesn’t float, so it’s not alive ».

In fact, in the world of kombucha :

• a SCOBY can float, sink, bend over and stick to the wall
• its behaviour changes according to its density, the temperature, the tea, the quantity of liquid
• it’s not a health thermometer in itself

What counts is what the drink does:

• Is the taste evolving towards more acidity?
• Is the smell pleasant, typical of kombucha?
• Does a new film form on the surface?

If so, it doesn’t matter that your SCOBY Natural Probio has settled at the bottom: the kombucha lives, the culture works, and a new SCOBY is slowly taking its place at the top of the jar.

By learning to look beyond this simple « it sinks, it floats », you really enter into the understanding of kombucha as a living drink. You see the whole system, not just a disc in a jar. And that’s where home brewing gets really interesting: less panic, more observation, more fun… and, in the end, more glasses of well-fermented kombucha to share.