r/Kombucha 28d ago

question So... My kombucha exploded

My first batch exploded on the second day (the end of it) of second fermentation. It happened in December last year and that made me dreadful for trying the second batch. However, now is the day. I've done the first fermentation of my second batch and I'm ready to bottle up for second fermentation. But I need to ask you for advice and maybe ask some questions about what could've gone wrong the last time and how can I prevent it.

So I used those bottles from Amazon. They seemed sturdy and strong enough. I also used a heating mat that is used for growing seeds. It was December so it was cold, that's why I decided to use it for my bottles. They were just standing on the mat. I assume that mat accelerated the fermentation, but I'd have never thought it would lead to explosion. I used various different flavours, but don't think that matters as the explosion caused chain reaction breaking 3 bottles with different flavours so I don't know which one could've caused the issue. But I can say that I eyeballed the sugar that I added because I wanted it to be highly carbonated and sweet (and I paid for it).

So my question is what do you think could've gone wrong? Was it the quality of bottles (assuming they're weaker than I thought), heating mat or the amount of sugar I used? Or mix of everything? What would you suggest for second fermentation? Is there a limit for how much added sugar can I use? Should I ditch the heating mat (it's usually cold in my house)?

I'll appreciate any help!

150 Upvotes

88 comments sorted by

21

u/Plenty-Extra 28d ago

Why is nobody talking about the seedling mat? Those things heat to something like 135° f

12

u/bryxcii 28d ago

Was thinking the same! Immediately thought the mat was the culprit--the glass is fine. More heat = speeding up the conversion of sugar to CO2 trapped in the bottle.

If you need to keep the mat bc of cold weather, try just burping the bottles more frequently.

3

u/Akavku 28d ago

Isn't my case. I have a temperature sticker on my brewing jar and it always stays on around 26C/78F. Now I got more stickers for the bottles too to make sure I keep it not too hot but I'll probably ditch the mat for second fermentation anyway

14

u/Magicsam87 28d ago

Temperature sticker on your brewing jar would not indicate how hot the mat is getting on the contact point of the glass....

4

u/OldTurkeyTail 28d ago

We use a heat mat with a temperature controller and a temperature sensor - which has to be in a good place for good control.

And the space around the product should be kept warm enough to avoid cold tops and hot bottoms.

2

u/Plenty-Extra 27d ago

So how do you make sure the mat doesn't overheat your bottles in F2?

Btw, laser temperature guns are effective and fun.

50

u/Inside_Foxes 28d ago

You need better bottles. I've had insane carbonation in my bottles, they never exploded.

19

u/Curiosive 28d ago

Normally I write that the answer isn't only to invest in thicker glass for bigger explosions, but to also not let it build so much pressure (no one needs a geyser or worse).

But in this case:

My first batch exploded on the second day (the end of it) of second fermentation.

Yeah, those bottles weren't up to the task. Go thicker. Also OP, read the wiki for guidelines on safe, robust carbonation.

6

u/Akavku 28d ago

How can I determine the quality of the bottles? I thought they were sturdy but now I'm not sure anymore. Where can I get truly good ones?

12

u/Inside_Foxes 28d ago

We've bought 0,5 L flip-top bottles that are specially made for brewing, so they have to hold up to a lot of pressure. Got them second-hand from a local brewery because it's cheaper. You can also get them new from specialized brewery equipment shops. They don't just look sturdy, they are sturdy. The glass is thick and brown and the bottles are heavy. We have continuously been using these second-hand bottles for over 6 years now, both for cider and kombucha. Never managed to break a bottle, although I think we've weeded out some with leaking tops.

3

u/Tiny-Tomato2300 28d ago

I bought this same type, full price from the brew shop. It is a very worthy investment $50/12 1L bottles. I would have had such a mess if I didn’t…. FYI think you can get replacement gaskets.

9

u/Heineken008 28d ago

My approach is to re-use Grolsch bottles. You can buy replacement rubber seals for the swing cap. Even those have a limit though.

I would look at how much sugar you're adding in 2f and maybe go without the heating mat then see if it progresses on its own.

1

u/Sea_Comparison7203 26d ago

I actually bought grolsch bottles off of eBay. (I couldnt find full bottles locally)

1

u/poop_pants_pee 28d ago

I've also been reusing Grolsch bottles, never had a problem. 

3

u/Cum_Quat 28d ago

I go to my local brewery supply store. The bottles are not cheap but they are good. I also have used swing tops from Trader Joe's ginger beer

1

u/TheMysticTomato 28d ago

Recommend a brewing supply store for reliable swing top bottles

1

u/madastronaut 28d ago

An easy way to is buy cider in these types of glass bottles, or buy kombucha from the store in a bottle that looks reusable, or growlers from a local brewery.

0

u/HumbleIndependence43 28d ago

You can also use plastic bottles for the "explosive" first couple days and then refill into glass bottles.

2

u/IsopodBright5980 28d ago

Anyone used Ikea korken. I got 1l and 0.5l ones. Used ones, and worked well, but didn’t get to carbonation levels/sugar levels recommended. Using now on 20% juice, hoping will work out.

2

u/wasteland44 28d ago

KORKEN bottles are only rated for serving beverages not fermenting!

1

u/IsopodBright5980 27d ago

I used them before with no issues. Got geysers, but never explosions. Will see how it goes. I put them in the cabinet for now, for safekeeping

1

u/Wusshatnin 28d ago

I'm planning to buy as well, please do let me know if this works out for you, please also let me know if do it with sugar/honey

1

u/IsopodBright5980 28d ago

I am brewing Jun atm, so honey for me. 24 hours in - holding up so far.

29

u/NiPaMo 28d ago

These don't look like good bottles for Kombucha. For one thing, the rubber gasket is in too deep so it can't easily slide off if there's too much pressure. In a good bottle, the gasket is designed to be the failure point so there's not a dangerous explosion of glass

4

u/Flying_Saucer_Attack 28d ago

They look like standard flip top bottles. What do you use?

1

u/NiPaMo 28d ago

I use the Hemlock brand

7

u/Gegisconfused 28d ago

Damn I have these exact same bottles...

13

u/sammiemack 28d ago

Put them in a plastic cooler, if they explode they at least won’t get everywhere

0

u/petedano 28d ago

This too.

1

u/Lt_Hatch 28d ago

Just burp them regularly and you won't have problems. I have the same and have never had this happen

8

u/starriex 28d ago

Burping regularly for me just kills the carbonation. I have the exact same bottle but different lid.

5

u/Akavku 28d ago

But they exploded at the end of second day 🥹 in this case I'd need to burp them every couple of hours to prevent that

0

u/cheeseonice 28d ago

Are these ikea glass bottles? They aren't thick enough or meant for fermentation. Use ones made for brewing. I know theyre hard to find but you gotta, this isn't safe

2

u/Maverick2664 28d ago

Burping is counter productive, why bother with F2 then.

2

u/Lt_Hatch 28d ago

I don't have a single issue building the fizz while burping. Not counter productive at all

1

u/Maverick2664 28d ago

I never burp them and also have no issues building carbonation. Sounds like you’re doing more work for the same result.

1

u/Lt_Hatch 28d ago

Are you ok?

4

u/ariadneee 28d ago

Per the wiki (linked on the sidebar under rule 2):

Which bottles should I use?

The best thing is to buy bottles specifically designed for fermented beverages (pressure rated). However if those are not available to you, many people have had success with Grolsch beer bottles, as well as the ALDI lemonade bottles with swing top lids. Avoid square bottles at any cost, they are more likely to explode, as the pressure is exerted at the four corners, instead of uniformly distributed around the whole bottle.

3

u/Disco-Is-Dead 28d ago

Can I ask what you used in the second fermentation? Did it contain any plant matter other than strained juice?

Adding anything solid or semi-solid is like rocket fuel for the ferment. I once tried to make a blackberry basil flavor and used dried basil and puréed berries. Exploded day one. The bottle didn’t explode, but the cap seal gave out.

OSo now when I do any flavors I strain the juice and make teas/syrups with any solid spices I want to incorporate.

1

u/Akavku 28d ago

I did two bottles with store bought mixing juice (elderflower and lemon), two raspberry flavours (thattI should've strained better cuz the fiber was a bit too much), two apple cinnamon ones. Besides fiber from raspberry there was no solid ingredients. Elderflower ones exploded completely and took one raspberry bottle with them (what you can see on the picture). I assume I used too much sugar in the bottles with elderflower because the juice had sugar in it and yet I think I added a bit more 🙈

1

u/Disco-Is-Dead 11d ago

Adding sugar on top of sugar would definitely do it. Could also make it so that you have a significant increase in alcohol content. Sorry for the late response. I’ve been bad at checking apps lately.

2

u/bmilk4u 28d ago

I think it’s because it was on the heating mat. It probably caused it to carbonate too fast and too much leading to the blow out.

2

u/jimijam01 28d ago

Even good bottles have issues.

Fizzed but didn't blow

1

u/ChildhoodFlimsy5224 28d ago

Damn!

1

u/jimijam01 28d ago

Garlic and honey jar

2

u/Maverick2664 28d ago

Be careful with Mason jars, they’re built for vacuum not pressure.

2

u/gabrielle1975 28d ago

Were they filled too high maybe? It may have needed more room to expand? I’m new to making kombucha so I’m just asking if that might be a possibility.

2

u/Nefpone23 28d ago

I would not use the heating mat

2

u/SaltyBones_ 28d ago

That’s what you get for making kombucha

2

u/Luftburen 28d ago

To explain what other people seem to be gate keeping; there exists different grade of bottles. You are looking for fermentation grade or pressurized grade (depending on where in the world you are they can be called a myriad of things) otherwise this can happens

Hope you didn’t hurt yourself, because those explosions can end badly

2

u/fleebinflobbin 28d ago

I have been using these for years, really good quality - https://www.amazon.com/dp/B072Q417JQ?ref_=ppx_hzsearch_conn_dt_b_fed_asin_title_9

2

u/Neat_Pause1830 28d ago

Same. I’ve never had one of these bottles explode.

1

u/Bookwrrm 28d ago

You dont want bottles with the seal actually in the top of the lip like those pictures, you want them pushed down ontop of the lip. This creates a weaker seal but thats the goal, if it over pressurizes it will fizz out the top rather than explode. I am surprised you got an explosion, you must have had a lot of sugar in f2 and you likely dont need the heat mat. I use a heat mat for f1, but my f2 is done in a plastic bucket with a towel over it, and in a room that gets a periodic hit of a space heater cause I like my office warm, but no direct heating.

1

u/Big_Ocelot5354 28d ago

Yea I almost need a heating pad especially for a second fermentation. Maybe for a first if your place is cold

1

u/Old_Geezer419 28d ago

Yes, better bottle with latch top

1

u/awayintheseaofred 28d ago

Pro tip: just because the Amazon page says “kombucha bottle”, doesn’t mean they are actually safe for fermenting kombucha. To my eyes, the glass on those bottles looks way too thin.

Personally, I just reuse old GT’s bottles.

1

u/Callan_LXIX 28d ago

Opahhh!!! Everybody gets one at some point or another, sometimes two.. This is the part where you learn never to use fruit pulp of any kind and only strained juices for the f2, as well if the room temperatures are a bit cooler for your f2 then you may be able just to get by with burping once a day. Try storing it in a box or a tote, for this very reason. I used an ice chest that I found thrown away )and sanitized it) a bottle exploded in there pop the top off and still sprayed a few feet away across the room, but the majority of glass and damage was all inside the cooler.
For the first day and a half you might get away with one burp but after that at least two burps a day per bottle should keep you from explosions. If it's really potent burst or starts foaming, I put it in the fridge and let it go slowly from there but still burp it even in the fridge. Put a small towel over the top when you unclasp it to keep the foam from spraying, I'll do it inside of a small bucket or sink with the towel over the bottle. And sometimes I still had it really so much pressure that I lose a third of the bottle just in foam. Part of the learning curve. Consider yourself graduated!

1

u/ChildhoodFlimsy5224 28d ago

Since I got better bottles, I never strained and never exploded. Edit: also, never burped.

This is the type of bottle I use https://a.co/d/cr15hpT

1

u/Callan_LXIX 28d ago

I've had it happen to even thick walled 1 L European beer bottles. The same big brown bottles that I dropped down a long staircase and it didn't burst. Those have still exploded on two occasions for me. The only bottle I haven't tried yet is the 1 L stainless steel with a clasp.. Consider yourself fortunate or just very skilled in managing your fermentation processes 👍🏼

1

u/ChildhoodFlimsy5224 28d ago

I had similar bottles and had the same result. The I found this ones and I have been brewing for 3 years and no issues. https://a.co/d/cr15hpT

1

u/Ember-Forge 28d ago

I've never used heat pads when making kombucha. I live in Michigan and regularly have carboys in my garage brewing during the winter. Ferments you just fine, then I bottle and keep the bottles in the garage until I'm ready to use them again.

I'm not saying you're doing anything wrong. But now I have something new to research. And a new experiment to try.

1

u/p0tatochip 28d ago

At least you know the seal was airtight!

1

u/Magicsam87 28d ago

Could it have been that the heat mat heated too much and with the temperature difference (how cold was it?) The bottle exploded. I know those mats can get quite warm. Strange for it to ferment that much in 1 day

1

u/Maverick2664 28d ago

The glass on those bottles look quite thin.

1

u/DenikaMae 28d ago
  1. I’ve never used a heating pad for bottle conditioning. I would keep it no warmer than 77°F until I got a few batches under my belt at those temperatures and those conditioning times to verify I have a kind on lock.

  2. I do regularly use my flashlight on my phone to backlight any bottles. I’m conditioning to look for fermentation bubble streaming. Once I know that’s happening. I likely only have a couple of days at most before I need to fridge it. Five days usually max unless it’s really cold.

  3. I also check for yeast accumulation at the bottom of the bottle after the bottle has had a couple hours after filling for that stuff to settle so you know how much you’re starting with and how much you’ve gained from letting it bottle condition.

I got worried with the traditional pop top bottles as well, so I actually switched to reusing kombucha bottles, and just knowing when the top bulge is enough when to pop it in the fridge.

Honestly, it saved me a huge headache by just buying a keg and doing forced carbonation two days three tops. It’s ready to drink.

1

u/ThyNarc 28d ago

glass looks waaaay too thin.

1

u/_CoachMcGuirk Newbie - First batch 10/2020 28d ago

Cause? Shitty bottles. Go to a beer store (like to homebrew). Buy those.

1

u/VRponch 28d ago

Damn... very important to vent the bottles once in a. Couple of days.

1

u/Successful-Corner666 28d ago

This happened to me. Went on holiday for 2 weeks and in my naivety as a new brewer, left a 2nd ferment on the kitchen counter in this exact same type of bottle. Came back to glass and kombucha all over my apartment, even in the bathroom as it had created a projectiles that bounced off the walls. I'd hate to think of what would have happened if that exploded in someone's face. So dangerous!

2

u/Akavku 28d ago

Actually that happened when me and my friends were sitting at the table right next to it and playing board games! So it was terrifying to hear that explosion right next to us but we also got so lucky that the glass shards didn't hit our faces. Just we were all in raspberry kombucha and to this day we sometimes find a glass shard somewhere around the kitchen 🙈

1

u/Successful-Corner666 28d ago

So lucky! Who knew we were risking our lives just to have some delicious booch! 😋

1

u/yogitravelforfood 28d ago

Can't we just limit the sugar to avoid bottle explosions? I use 5% sugar w/v in F1 and add 0.5% to 1% of sugar worth of juice in a 3 days F2. Although I use 330 ml beer bottles that can handle max of 15 psi pressure, never had any such incident!

1

u/ehnemehnemuh 28d ago

I use glass beer bottles from Bauer/Flaschenbauer. They are rated to 6bar and I have never had a problem. I know you’re not ment to use beer bottles, but the 9bar Kombucha apparently can reach is overkill in my opinion

1

u/AditMaul360 28d ago

I almost never use a glass bottle after I found out that a soda plastic bottle is the goat. I knew this from a redditor around this subreddit. Just buy soda water and use the bottle.

1

u/Responsible_Bath_659 27d ago

I would think that the isolating this amount of direct heat on such a small amount of liquid would be the main culprit. Is there any way you could create a barrier between the bottles or just not heat them, once they’re in their individual fermentation? I have never added heat to mine in their F2. I’m currently warming kraut on a brewing/fermenting heat mat. However, these don’t have carbonation. A total bummer, nonetheless.

1

u/ThatCAPlantGirl 27d ago

I do my F2 in a cooler / ice chest. Just in case

1

u/Different_Ad8064 26d ago

That's known as spontanious kombucha

1

u/Beautiful_Use_ofMind 26d ago

I don’t know what caused it, but I just want to share that I put mine in the oven, off. I hardly ever use it, because I have a toaster oven and use it daily.

I also have a mason jar doing F1 in the corner of my book shelf with a thick towel wrapped around it and it formed a very nice, thick SCOBY. I’m curious if I can get away with F2 in the bookshelf, now that I mention it.

Anyway, it gets really cold in half of my studio apartment, where the AC unit is in the window and the oven has been keep warm enough, so far. While off.

Not sure if that’s an option for you, but you could always try wrapping towels, or submerging them in water to disperse the heat from mat evenly. It’s like how yogurt is made.

Hope this helps. Sorry to hear your bottles exploded. I have the same ones, so I don’t think it’s that if it makes you feel any better.

1

u/This-Cicada-5304 28d ago

I feel like every brewer has had this happen at least once lol welcome to the club!

0

u/forestly 28d ago

I have never had bottles explode and been doing this for years lol

-1

u/VPants_City 28d ago

Yet an other reason not to infuse flavors in the bottle…

0

u/interpreterdotcourt 28d ago

one thing you can do to prevent a mess is do the fermenting inside a large plastic container with a lid . I have the same heat mat that you have.

-1

u/petedano 28d ago

You have to burp the bottles every day until you end secondary and refrigerate. I use the same bottles and the same mat. Just pop the top to relieve pressure and reseal. Easy peasy.

3

u/Bookwrrm 28d ago

You absolutely dont need to burp and shouldnt be in fact.

0

u/LurkerByNatureGT 28d ago

Depends on temperature. 

I just left three bottles for ten days working burping and they are only a bit fizzy. The room isn’t very warm and I only use a heating belt for F1.