Fizz Factor: How to Increase Carbonation…For Advanced Brewers

This post is a follow up to Kombucha Bubbles: How to Increase Carbonation…for Beginners. If you are looking to increase your fizz factor while brewing Kombucha, try those techniques first and if you are still unable to achieve the carbonation you are looking for, only then try those listed below.

These methods are intended for the more experienced Kombucha brewer and even then only for those who have extra cultures to experiment with.  I recommend using one method at a time to see how it works and avoid over yeasting your brew.

First though, to understand what we want to accomplish, let’s take the opportunity to more deeply explore the yeast/bacteria symbiotic relationship!

The Yeast/Bacteria Relationship

The bacteria and yeast in the starter culture work in symbiosis to transform tea and sugar into fermented Kombucha tea.  The yeast consume the sugar and create ethanol (alcohol) and carbon dioxide (our fizz factor!), then the bacteria consume the ethanol and convert it into healthy amino acids.

The balance between the yeast and bacteria can be a delicate one.  If there is too much yeast in your brew, it can cause the bacteria to struggle; the other way around and your brew has little to no fizz.  As always in life, strive for the ideal balance for optimum results.

A brown and white Ying-Yang demonstrates balance.

Symptoms of an unbalanced Kombucha brew that may need a yeast boost:

  • Kombucha sours slowly or takes too long to reach the desired tartness

  • Little SCOBY growth

  • Lack of carbonation

What is Yeast?

Microscopic close-up of the s.cerevisie yeast body shows the tiny buds beginning to form. These will eventually become new yeast cells.
Notice the buds coming off of the S.cerevisiae yeast bodies, this is how they reproduce.

Yeasts are single celled organisms that have been used in baking and fermentation for thousands of years.  They belong to the kingdom Fungi (Kombucha is not a mushroom, people!).

Each Kombucha culture has its own variety of bacteria and yeast; though all of them will have acetobacter and saccharomyces, the exact composition may vary.  Some of the common strains of yeast in the culture include: Saccharomycodes ludwigii, Saccharomycodes apiculatus, Schizosaccharomyces pombe, Zygosaccharomyes & Saccharomyces cerevisiae.

DID YOU KNOW?  “Saccharomyces” is derived from Latinized Greek – saccharo- “sugar-” and myces “fungus”. Cerevisiae comes from Latin and means “of beer.” Cerveza anyone?

The yeast are the brown strands or strings that you find floating attached to the culture or collecting at the bottom of the jar.  They thrive at lukewarm to mildly warm temperatures which is the reason why the tea solution must cool prior to adding the culture.  Too hot and they die off.  Yeast release CO2 and ethanol.  It is the CO2 causes bread to rise and gives beer and Kombucha its natural fizz.  Roll up your sleeves and let’s go yeasting!

Warning: Remember, Kombucha bottles may explode if left unattended. Kombucha CO2 can build up quickly, especially with these techniques. Bottles must be monitored and burped, and it is recommended that one takes extra care when using these techniques as the increase in yeast activity can be significant. Store your secondary ferment bottles in a cooler, box or small enclosed cupboard to prevent additional damage. While I have never experienced an exploding bottle, I have heard the stories.

Brown strings of yeast collect at the bottom of the vessel and on the SCOBY. They help increase carbonation in your Kombucha brew.
Yeast strands are brown and collect at the bottom of your brewing vessel

Yeast Manipulation Techniques for Increasing Carbonation

Take Starter Liquid From the Bottom

Yeast is distributed throughout the Kombucha, whether you can see it or not. Once the yeast have done their job, they collect at the bottom of the brewing vessel. When they join together, they form the brown strings you see in the photo.

Normally, in order to preserve a healthy balance of bacteria & yeast, the starter liquid is pulled from the top.  This ensures that we don’t over yeast the brew (a lesson I learned the hard way).

However, if we are looking to boost our yeast quotient, the best place to find them is hanging out towards the bottom, which makes gathering them much easier.  Here’s what you do:

  • Pull 2 cups of yeastie starter liquid from the bottom of your brewing vessel.
  • When you have completed your brewing process (use 1 cup less water to accommodate the extra starter liquid), add the yeastie starter as the last step.
  • Cover and if possible place near a source of warmth (heating mat, warm stove, in a crock pot on low, etc) to keep the yeast active.
  • You should notice more carbonation within 1-2 brewing cycles.

Increase the Amount of Tea

The caffeine present in the tea will stimulate the yeast to remain active rather than allowing them to take their normal rest cycle.  Add an extra teaspoon or two (1-2 tea bags) of green or black tea to achieve the desired result.  Green tea has been noted for its ability to boost carbonation but my experience has shown me that the culture prefers a variety of teas to thrive – so don’t be afraid to mix it up.  Check out this blog post for more information on the best teas to use for fermenting Kombucha.

2-Stage Fermentation

This technique is described by Len Porzio of Balance Your Brew. I have never tried this method: mainly because I go with the flow – sometimes my brew is super bubbly and other times it is more flat and I’m cool with that. Len is a muy respected Kombuchero, so let’s see how his method works:

  1. Filter the fermented KT with a cheesecloth into a plastic bottle (a 2 Liter soda bottle works great for this) – you don’t want to prevent all of the yeast from getting through, this is just to remove the ooglies.
  2. Fill the 2-liter bottle all way to the rim with the KT.
  3. Gently squeeze the bottle to remove excess air before capping.
  4. Allow the bottles to remain at room temperature.
  5. Check the amount of carbon dioxide pressure building up by squeezing the bottle.  You want it to feel hard, like a basketball.  This process usually takes 1-2 days but may take longer if yeasts are lacking.
  6. Once your bottles are hard, transfer them to the fridge to deactivate the yeast (go dormant) and reduce the amount of pressure that has built up.
  7. After a couple of days in the fridge, gently pour the liquid into glass bottles.  You should notice fizzy bubbles as you pour, but do not pour so fast that it froths in the bottle.
  8. Take care not to allow the spent yeast that has collected on the bottom to enter the bottles.  Discard the spent yeast.

Len sez: Don’t Forget: Fill your bottles up to the rim & sample your brew when pouring from plastic to glass- if too tart, add some sugar or agave to mellow the flavor.

Crabtree Effect

The Crabtree Effect is not an overpriced soap store or a bad 70’s action picture. In fact, The Crabtree Effect is a normal part of the Kombucha brewing process. It occurs when an excess amount of glucose (sugar) is introduced too quickly to the yeast.

Much like a typical family after Thanksgiving dinner, the yeast fall into a “food coma” and stop reproducing.  Usually, this is great as it allows the bacteria to kick into gear and maintain balance. However, if we want the yeast to keep working, we need to prevent The Crabtree Effect from occurring.

To prevent your yeast from passing out on the job, gradually add the normal amount of sugar over the course of three days.  This allows the yeast the chance to keep up with the amount of glucose present in the nutrient solution.

Here’s what ya do (all measurements based on 1 cup of sugar per gallon of nutrient solution, scale to fit your needs):

  • Day 1, add 15% of the sugar = 2-1/2 tablespoons
  • Day 2, add 30% = 1/3 cup
  • Day 3, add the remaining 55% = 1/2 cup + 1 tablespoon

Now you’ve got loads of tips and tricks to try next time you are feeling like your brew is falling flat. 

Have you tried any of these techniques?  Did you get loads of carbonation?  Have other tips for boosting the bubbles?

Share your story in the comments below =)

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Responses to Fizz Factor: How to Increase Carbonation…For Advanced Brewers

  1. I’m on my 3rd batch and loving it! I’m experimenting with flavoring and have found that using candied ginger (found at our local earthfare grocer) really packs in the co2. Maybe a combination of the ginger and sugar? The ginger combined with fresh squeezed lemon juice and raspberries is great and it’s very, very similar to GT’s trilogy. My other favorite flavor is GT’s gingerberry and here’s what I use to match that flavor: sliced kiwi, candied ginger, and fresh blueberries. Both of these create a great amount of co2! Yum. And thanks KK for walking us through this process in an easy step by step format:)

  2. Hi! My second fermentations have a lot of fizz when I test them at room temperature but lose it all when I strain them and refrigerate. Should I not refrigerate them? My Ginger brews are really good and I made an awesome pumpkin spice brew… But the fizz once stained! Please help, friends are requesting but I don’t want to give flat gifts.

    • Yes – yeast are temperature sensitive. So if we put the Kombucha in the fridge, because the carbonation is natural from the yeast, it can go away. Easy fix – take it out of the fridge and leave on the counter for 20 minutes or longer until you see the bubbles returning. We store our Kombucha in a cool closet rather than the fridge and then pour over ice if we want it cold. Hope that helps!

  3. Oh no! I wonder if I damaged my scoby by adding too much sugar to my first batch and having the tea too hot for the second batch. Neither batch fizzed. My second scoby did fizz though. :-/

  4. How would I add hibiscus to the brew? In as a “steep” with the tea bag and remove it before putting the tea into my crock or let it sit the whole time the brew is fermenting? I’d like to try to perk up my cultures as you had stated earlier in this thread.

  5. After trying many methods my brew is flat. Althjough my kombucha looking healthy but do you think they are somehow contaminated in a way they dont do as well as others? Should I get a new kit to start ?

  6. How do you add sugar on days 1, 2, and 3? Is it dissolved in water then mixed in, or can you just sprinkle it in and stir it up?

    • It is best if it is in liquid form – so making a simple syrup of 1 part sugar and 1 part water would be the best way for them to receive it. If that is too much trouble, simply nudge the culture aside, add the sugar and give a quick stir. The SCOBY will regain normal formation once it is left undisturbed.

  7. I bought some brandied cherries at a deli in town. Smashed them and put them in with smashed raspberries. That brought about a nice bite. But the best so far for me has been using my homemade jelly for flavor and sweetness. Everything else I have used never seems to get sweet. My Honeysuckle Jelly is my favorite. Probably all I will be using from now on.
    Love your site. Thanx.

  8. hi hannah,i have been brewing for about a year,i had been doing very well with it untill the cold weather hit and it has been going down hill since.i not only have no fizz the baby soobies are so thin they are not worth even saving them….any ideas as to what i am doing wrong….thanks so much Anne!!

  9. I’ve been successful with the continuous brew & second fermentation method now for a few months. The question I have is, how do I get the same effects as I did from the store bought K. The store bought K helped me not be so sleepy throughout the day, it gave me such a sense of energy and focus, and I was less hungry. I’m using the black oolong tea. Ant ideas would be appreciated. Thanks!

  10. Do I keep putting the scabies I purchased from Kombucha Kamp in my brewing vessel every week, or am I suppose to dispose of them? I am on the 4th week of brewing. Each week a new scoby layer grows on top of the vessel. The original scoby lays in the vessel and looks the same.

  11. I love your site. My CB brews very quickly as I live in SW Florida and I will start stirring before decanting to help slow it down. I add an ounce of 100% juice to my 16 oz bottles then add hibiscus and other flavorings. 2 days on the counter the into the fridge. If I want super bubbles after the second fermenting I rebottle with some hydrated chia seeds in about an hour it is like soda.

  12. Thank you so much for the time and effort you put into this site. I received my Scoby from a lovely friend and my first batch was wonderful. After that, however, it took forever to ferment with a thin scoby. After reading MUCH (have I come to the end of the internet yet? lol)I discovered that we keep our house too cold (down to 65 at night). I added a heat source by sitting my jars on a chair over a heat vent and covering the whole thing with a sheet. They are now fermenting happily. My favorite flavoring is Ginger, grapefruit and a touch of honey. Oh my goodness! Thank you again. I love this site. It is the best!

  13. I may have gotten the ratios of starter KT to new batch wrong in my CB. I’ve been using the CB for a couple months, and have never gotten the end result that I had using a regular gallon jar. The first batch in my CB I left for a few days before tasting it and it was quite vinegary. So each time I make more, I start tasting it the next day, and it’s always more vinegary than I like it. The last few batches have been pale in color and with very little carbonation, even adding fruit juice to the 1st bottling (I use the heavy glass jars with the locking flip-top lids). The end result is more sour than I’d like and with very little carbonation. I always use the same tea, Darjeeling and oolong mix.
    Gratefully, I had started a hotel, so just today made a brand new batch in my gallon jar, using a new Scoby and some KT from a few batches ago when it was darker and more fizzy.
    Any ideas what might be going on?
    I’m loving making my KT, I drink at least 16 oz a day, and really would like to get the hang of the CB.

    • If your CB is souring too quickly, that is usually a sign that it is time to clean it out as the yeast has built up on the bottom.

      Stirring the CB just prior to decanting will help with both of these problems. When we brew in a jar, in order to remove the Kombucha, it is upended causing the yeast on the bottom to get into the bottles. Then, when the fruit or sugar is added, that yeast reactivates to create the carbonation.

      You may need to reset your CB now and then in the future, stir before decanting to get the carbonation you are looking for and to keep the CB balanced.

    • Nearly everything with Kombucha is to taste. For instance, we never put our KT in the fridge as we prefer to let it bottle age. It will continue to ferment in the bottle and the flavor will shift over time. If you have flavorings in your bottles, you will want to move them to the fridge to prevent off flavors or you might strain out the flavoring if you intend to let the bottles age for longer periods of time. As for dried or fresh – they both work great! I like using the fresh herbs from my garden, but also used dried flowers and barks as well. Happy Brewing!

  14. Hannah,
    I realize that I have not been filling my bottles to the top. Thus no carbonation. However, there is carbonation when I draw a glass of tea from the brewer to drink. I have used pureed strawberries and pureed peaches to flavor the KT for the second fermentation. Again, no carbonation. In the future, I will add some sugar to the pureed fruits and fill the bottles to the top to be sure that I get carbonation. Also, the pureed fruits are great added to a glass of KT from the brewer.

    Thank you for the excellent information and support on how to get started and how to keep on doing (brewing)!

    • Give your CB a quick stir to get the yeast from the bottom into the liquid. Then when you decant into your bottles, you will have yeast strands present which will help you increase your fizz. Let us know how that works for you!

  15. I am so glad I found your site. Thank you Hanna for all the helpful I formation. I am currently experiencing carbonation issues. I can’t wait to try some of the tips I learned here today.

  16. hi, thx for info, i guess due to occurrence of carbtree effect my kombucha got bad, cuz i was introducing lots of suger while making it & was not aware that yeast may stop working…

    again my neighbor had nice result when she use this proportion 8 cup water (approx 1 ltr) less then 1 cup sugar, & hardly 1 spoon of tea.

    this way her KT gets bubbly naturally..

    thx again for sharing & making this page.. 🙂

  17. Vic – I grate my ginger, sometimes large or small grate where it’s almost ginger juice I’m adding! I am careful though and only leave 3 days then strain off and rebottle leaving for a period of weeks, burping everyday. I jumped into continuous brewing right off, never have carbonation issues since I bottle twice, once for flavouring and once for melding and mellowing of flavours. I just love this whole process. Thank you so much Hannah for your time and energy in sharing your KT expertise. I’ve found your website has been so helpful these past months since my first tasting of homemade kombucha. I now have over 9 gallons in 4 separate vessels of continuous brewing on the go. Not all for me though. LOVE IT! Robi

  18. I reserve 2 cups of liquid for my next batch and have consistently found my brew to have great carbonation. But is this too much liquid? The reason I ask is because I use green tea and my scoby’s are not very large nor thick. When I used half green tea and half black tea, the scoby’s were thick and white… just beautiful! BUT the black tea caused an old medical issue (intersitial cystitis) to flare its ugly head so I went back to green tea only. Would you have a recommendation for another tea to add in with the green tea to still get a healthy scoby? Yerba mate and the white peony tea seem a little pricey (for our budget) for the 4 gallons we make weekly. Thank you!

    • 1-2 cups per gallon batch is an appropriate amount of starter liquid. Everyone finds their ideal recipe based on their personal preferences and needs. Yerba mate would be the best substitute for the black tea as it is high in nitrogen. Hibiscus can also be used in the primary fermentation and yields beautiful pink SCOBYs. Switching up the nutrient solution for your cultures from time to time will also perk them up. Or brew a batch of black tea for your SCOBY Hotel to keep them happy. You can use the liquid as starter to bolster the fermentation while minimizing your exposure to the black tea. As always, trust YOUR gut!

      • How would a person use hibiscus in the primary brew? Would you steep it in a bag or ball when steeping the tea? I use hibiscus and ginger together in the secondary fermentation but am interested in what you are saying about “perking up the culture” as mine have not been getting very thick.

  19. I’ve been putting in 1 rather large slice of fresh ginger to my bottles. Maybe that’s why I’m not getting much fizz. Those of you who put small pieces, do you strain your kombucha before drinking or do you just drink those small pieces of ginger?

    • You can strain out the flavorings or not. Adding a small amount of sugar as primer for the yeast will help increase the carbonation. In a 16oz bottle, 1/4-1/2 tsp of sugar will work.

  20. I have a very thin baby in brew of 7 days. Could I pour some liquid from my hotel over brew and let stand for a few days more? Would this make a healthier scobie? Also take up more sweetness?

    • This time of year, it is difficult for the Kombucha culture to reproduce and to make properly flavored due to the colder temps. Adding more starter may not increase your SCOBY’s size but it would help consume the sugar in your brew. We recommend using a heat source to keep your cultures viable through these colder months.

  21. I just did my second c/b–poured my gal of second brew into the top where my scobys had happily spread themselves across the entire opening—well by pouring I disturbed the mother and now on day 3 of second brew she is still all folded up hasn’t spread across to reseal—will this effect my carbonation—and how do I pour into with out disturbing the scoby?

  22. Thanks for all these tips, but I’m in search of what to do when you have too much carbonation and yeast production? I’ve been brewing for several weeks now and can not seem to produce a baby scoby. I’ve reduced the steeping time of my tea, I’m taking the starter from the top, but still with no luck. Any thoughts? Thanks!

  23. I am still playing with my brews to get more carbonation and notice that when I add ginger to a brew it really increases!!

  24. Hannah, love your two pieces on carbonation, thanks. I totally agree that a heightened sensitivity to carbonation levels is acquired by home brewing Kombucha. In the beginning, I did a lot of research on the topic to make sure my bottles were nicely carbonated but now that I’m also doing continuous brewing, I find I enjoy the more subtle ferment also.

    Recently I’ve started adding pineapple to my second stage ferment and the carbonation levels are super high. Oh my god, it froths forth like mad. During the second ferment stage; I find that ginger & lemon alone add quite a bit of carbonation so I usually make these two ingredients my base and then add herbs like sage, rosemary, thyme. The most carbonation so far has come from adding pineapple.

    I believe the high level of enzymes in ginger, pineapple and papaya encourage added carbonation. They have proteolytic enzymes that break down proteins; pineapple has bormelain enzyme, ginger has zingibain enzyme, papaya has papain enzymes. Bacteria and yeast are protein/ amino acid-based. Proteolytic enzymes digest bacteria and yeast. Carbonation results from this break down.

    This enzyme theory makes a lot of sense especially given that ginger beer and fermented pineapple are ancient effervescent elixirs. A biochemist on our team could add further insights.

    • Hi Victoria,

      Do you add whole pineapple slices, or fresh pineapple juice.

      In general with fruit is it better to add, pieces, puree, or juice?

      Thanks so much!

      • The smaller the size of the flavoring agent, the easier it is for the Kombucha to absorb the flavor. By that logic, juice or puree would yield the most pineapple flavor. Let us know which you use and how it turns out!

        • Hi Victoria and Hannah,

          I have been brewing Kombucha at home for many years now, both plain and 2nd ferments. I have discovered, just like U said Hannah, that smaller sized flavoring agents work best. To me, this means concentrates. There are plenty of concentrated juices in ur grocery store frozen food section to choose from. When I make pineapple 2nd ferments I have to be extra careful to watch for the pressure or they will explode violently.

          I have used fresh, raw fruits as well; like blueberries and dark cherries. These tend to create more subtle flavors. They’re very pleasant, yet clearly on the mild side. because I share my brews with family and friends, I get calls for flavors that are more upfront, and this is why I have moved to the concentrates. I make a grape that’s actually better than GT’s Divine Grape!!!

          Hope this helps…

  25. I just wanted to 2nd the thought that the bottles can and will explode. I’ve had two of my GT bottles explode and I was thankful both times that no one was near them. I do not keep them in a box orcontainer, but in a room all to their own. I’ve always feared that they might go off just as I’m putting them in the frig.

    Thanks for all the tips.

    • That is why it is an excellent to let the pressure out even a couple times a day am and pm I have a glass wine bottle with a plastic screw push in type top one day it was laying on the floor when I let pressure out in the morning it popped so didn’t surprise me it forced the top off. Later in the day

  26. Thanks for listing these, I sometimes can’t get the carbonation the way I like it and I am going to give some of these a try… Love your site!!

    • I have only been brewing for a month and just poured up my second batch. But both have been fizzy. I can’t explain why. I just add sugar and tea to scoby with kt and cover with cloth. Guess the mother I received was a really great one.

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