My SCOBY Is Too Thin! Here’s What To Do

Another common question in my brewing groups concerns thin SCOBYs. The scenario is usually something like this: they’ve brew a number of batches yet they can’t seem to grow a thick SCOBY.

Alternatively, this is their first batch and they’re wondering why their new SCOBY isn’t growing as thick as they’ve seen in pictures.

Whatever the case, this article will help clear the air and get things back up and running. To start off with, let’s set things straight – is a thin SCOBY necessarily a bad thing?


My SCOBY Is Thin – Should I Be Worried?

Before we get into the article let’s make sure we’re clear on two points right from the beginning:

  1. If your kombucha brew is less than 7 days old and your SCOBY is thin just wait a little longer, it will grow!
  2. Baby SCOBY can be only a few millimeters thick after the 7 days – within a few more batches they will grow thicker.
  3. If you’re still getting great tasting kombucha that you’re happy with then there is nothing to worry about.

With that out of the way, let’s cover a few SCOBY basics (if you’re interested in learning more you can check out my article here.) First off, what exactly is the SCOBY anyway?

You may be surprised to hear that the SCOBY is actually almost completely made of cellulose. The cellulose is woven together by the acetic acid producing bacteria within the kombucha. Over time, it serves as a safe haven for both the bacteria and the yeast.

The yeast provides the food, while the bacteria supplies the home.

The reason why the SCOBY is so crucial to brewing kombucha is it provides the necessary balance of yeast and bacteria to get the new brew started – the actual shape of the SCOBY doesn’t really matter!

In fact, you can cut your SCOBY up into little pieces, as long as the quantity is right you should notice no difference in your brew.

This is where we run into the first issue with thin SCOBY – the size.

Ideally, you need the right kickstart to every new brew. This primarily comes from the strong starter liquid, but the SCOBY still plays an important role. If you don’t have the right amount of SCOBY present your brew can get off to a slow start.

This is one of the reasons why so many people struggle to grow a larger SCOBY when they only have small SCOBYs available. The time required for the SCOBY to grow usually is so long that the kombucha turns to vinegar.

Why Brewing With A Thin SCOBY Can Be Difficult

It takes time for the bacteria and the yeast to develop. So it makes sense why brewing with a thin SCOBY takes longer than with a regular SCOBY.

Just imagine if you significantly cut back on the start yeast and bacteria of your brew – the entire process will just be slower.

If things start off balance it can lead to a number of problems along the way. One example is your kombucha turns to vinegar much sooner than expected. This is usually a sign that things aren’t balanced and action must be taken to bring things back into equilibrium.

This is one of the main reasons why people are getting stuck in an endless loop of thin SCOBY! If you don’t have the right starting ratios things may not go as expected.


Reasons Why Your SCOBY Is Too Thin

There are a few reasons why your SCOBY may be having difficulty growing. They are:

  • Weak starter liquid
  • Cool temperatures
  • Low populations of bacteria
Red is the starter SCOBY, blue is the first baby and the white is the second baby

Weak Starter Liquid

One of the most common mistakes new brewers make is not using strong starter liquid. Starter liquid is the sour kombucha we use to kickstart the brewing process.

Two cups of strong starter liquid is dumped into new brew to ensure the correct balance of yeast and bacteria is present right at the start.

The key word here is strong. You shouldn’t be using regular strength kombucha as your starter liquid.

Pro Tip

Don’t use regular strength kombucha as your starter liquid

The best case scenario is taking your starter liquid from your SCOBY hotel. The second preferred method is to let your leftover kombucha turn to vinegar. The easiest way to do this is to let it sit with your SCOBY for at least another 7 days after you’ve bottled.

A thin SCOBY is a sign of weak starter liquid – you just didn’t have the right kickstart your kombucha needed!

Cool Temperatures

Remember, the bacteria supply the home while the yeast supply the food. If there is no food for the bacteria they won’t be able to build the SCOBY.

What are two ways you can cut yeast production?

  1. Cut down on the sugar you use
  2. Cool the temperature

Similar to homebrewing beer, the temperature of your yeast is crucial to their productivity. Experienced brewers will tell you how their brews take just a little longer during the winter months.

This is due to the lower average temperature of your brewing vessel.

Now, if the temperature is too cool you are going to be hurting the yeast. We want to be aiming for a temperature between 68-78°F. If you are consistently below this range your yeast will not be producing the food the bacteria needs.

Pro Tip

If you’re brewing during winter try wrapping non-LED christmas lights around your vessel to raise the temperature

Low Populations Of Bacteria

While rare, it’s possible for the bacteria populations within your brew to die off. This may be due to other strains of bacteria being present or if your brew has been exposed to anti-bacterial soap.

Note, it’s fine to use soap to wash your brewing equipment, just make sure everything has been thoroughly rinsed.

This cause is hard to diagnose, so don’t be worried right off the bat.

If you’ve tried all my suggestions below and still can’t seem to work things out you are going to want to get a new SCOBY with a new set of starter liquid.

You Used The Wrong Type Of Tea

One of the most fun aspects of brewing kombucha is the flavoring. It’s exciting mixing and matching different flavor profiles and tasting the results.

This leads to many beginner brewers using flavored teas during the primary ferment.

You may be surprised to learn that this isn’t best practice. In fact, the essential oils in the flavored tea can even be harmful to the bacteria and yeast populations in your brew.

This is why I don’t recommend you use 100% flavored tea during your primary ferment. Using a home made tea blend is fine (try and shoot for a least 50% Camellia sinensis with each blend.) Find out more here.

Alternatively, you can mix the flavored tea into the bottles during the second ferment.


How To Fix A SCOBY That Is Too Thin

Before I dig into how to fix your thin SCOBY it’s important that we ask one question: are you getting kombucha that tastes the way you want?

If the answer is yes, then I recommend you just continue on brewing.

If your kombucha is lacking in anyway then you can start troubleshooting. I don’t want you to be worried just because your SCOBY doesn’t look right. If you’re using strong starter liquid then you will likely be able to brew kombucha that is perfectly fine.

As the saying goes, there’s no point on trying to fix something that isn’t broken!

Let Your Brew Sit For Longer

My first tip to thickening your SCOBY is to let it sit in the brewing vessel for longer. They way you should do this is pour in the same amount of starter liquid and sweet tea, but instead of bottling the kombucha after 7 days let the brew sit for at least 14.

Hopefully, this gives your slow SCOBY enough time to fully develop.

If your SCOBY is still too thin to your likely then just repeat this process once.

If this fixes your SCOBY you could be dealing with low brewing temperatures or an imbalance of either yeast or bacteria.

Use More Sugar

If you’ve been using 1 cup of sugar per batch, try 1.5 cups. You can even try 2 cups and let your kombucha sit for an extra 2 days (9 days instead of 7) to see if your SCOBY develops.

This solution means your yeast wasn’t getting enough nutrients. If your yeast is struggling, so is your bacteria. Remember, it’s the bacteria that produces the physical SCOBY.

If you’re having yeast problems you can also try and scoop your starter liquid from the bottom of your SCOBY hotel. This is where the old yeast lay dormant until woken up with fresh sugar.

Use A Strong Starter Liquid

Take the starter liquid from the top of your SCOBY hotel if possible. Otherwise, you should let your first batch of kombucha turn to vinegar.

This will ensure you are always using a strong batch of starter liquid that kickstarts your SCOBY into high gear.

I usually let my leftover kombucha sit for several days before I start a new batch brew. This ensures the yeast and the bacteria are hungry for your sweet tea and will begin producing kombucha (and a new SCOBY) immediately.

Replace Both Your Stater Liquid and SCOBY

The last resort is to replace your building blocks: the SCOBY and the starter liquid.

If things have somehow become unbalanced, through contact with a foreign strain of bacteria, mold, or other harmful substances, then it will be very difficult to produce regular kombucha.

The best way to solve this issue is to buy a SCOBY and starter liquid from a different source.

If you decide to go this route I also recommend only using black tea with the correct brewing temperatures and sugar ratios for your first few batches – leave the experimentation for when you have a backup supply of healthy SCOBYs in your hotel.

Thankfully, most people don’t have to go to this length to get their kombucha brewing back up and running.

If you are still having issues, or have other suggestions, please contact me in the comments below!

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