We’ve been brewing kombucha on and off at home for several years now, the problem was that we started small (1 gallon) and our family of five would tear through that amount in no time. So from there, we scaled up and started brewing 5-gallon batches (as a homebrewer, that was the next logical step for me as 5-gallon batches of beer was my starting point as a homebrewer; so why not do the same for kombucha?).
The problem with 5 gallons was that it’d end up sitting in the keezer too long if the flavor that we chose to add wasn’t a family favorite. So, now I’ve landed on using the Ss Brew Bucket Mini in order to create 2.5 to 3-gallon batches to fill a 2.5 to 3-gallon keg.
Now that we had our new size dialed in, my next concern was maintaining temperature. We live in Southern California, so leaving the kombucha to ferment in the garage isn’t a good option as it gets a bit too hot out there. Last summer, we had tried that with a batch and it was overrun by Kahm yeast (I’m trying to find a picture of that to share). Most people seem to ferment kombucha in the house, as they’re able to find an area that is 75-80 degrees Fahrenheit, but, you see, my wife likes to sleep in a house that is a balmy 68-70 degrees, so our air conditioning is generally cranking all night.
How to keep kombucha warm in winter or in air-conditioned spaces?
70 would be a great temperature to ferment an ale at, but kombucha likes it a bit warmer. I’m shooting for 78-80 Fahrenheit. The garage might work during certain times of the year, but not always is it’s been in the 90s here the past couple weeks and our garage seems to match or beat the outside temperature. So I needed to find a way to ferment in the house while modulating the heat on the fermenter. Luckily I had a few Ss Brewtech parts laying around that I could use to make this happen.
Here’s a complete list of items that I’m using for our (max) 3.5-gallon kombucha fermenter:
- Ss Brewtech Brew Bucket Mini
- Ss Brewtech Brew Bucket Mini Kombucha Lid
- MTSs – Mash Temperature Stabilization System
- 17mm Hole Saw (to add a thermowell)
- Short Weldless Thermowell / Long Weldless Thermowell
- Optional – 17mm Hole Plug (if you ever decide to remove the thermowell)
Setting Up the Brew Bucket Mini for Kombucha Fermentation
Just like fermenting beer, kombucha ferments better within a specific temperature range. Getting to the upper and lower limits of that range can create off-flavors and getting outside of that range can prevent fermentation altogether. The best chance at good fermentation is having a good temperature control system in place.
Installing a Thermowell to Monitor Temperature
I started by locating a spot for the thermowell. Once I decided on the location, I used a hammer and a punch to make a small indentation to help keep the drill bit in place. I loaded the 17mm hole saw into my drill and began drilling a hole for the weldless thermowell.
The hole saw made quick work of adding a 17mm hole into the side of the brew bucket. It did a pretty good job, leaving the edges slightly rough which were easy enough to clean up using fine-grit sandpaper.
Next up was testing the thermowells to see which one I wanted to use. I happened to have both a short and long thermowell on hand, so I inserted both for reference.
The short thermowell would probably be fine for this sized fermenter, however, I opted for the long thermowell as it reaches just about to the center of the Brew Bucket Mini. I figured having a reading from the dead-center of the fermenter might be a little more accurate in our house since the outer edges would be exposed to the frigid air from the air conditioning.
Installing a Heat Source to Maintain Consistent Temperatures
After the thermowell was installed, I stuck the MTSs heating pad to the bottom cone of the Brew Bucket. Side note: I stole the MTSs from my InfuSsion Mash Tun since we recently added a RIMS Tube to our electric brewery. Since the heating pad had already been used on another vessel, it lost a bit of its stickiness, but that was quickly resolved by adding a small piece of duct tape. The heating pad overlapped a bit, so the duct tape was used to help prevent it from peeling back – it didn’t like sticking to itself.
With the heating pad in place, I flipped it over and made sure that it still fit in its rubber boot – there were no issues there, so now there were just a couple things left to do:
- Get the new Brew Bucket Mini Kombucha Lid ready by fitting the screen over the 6″ tri-clamp port. The screen fits very snug, you may need 3 (or 4) hands to get it on.
- Set the MTSs controller to specify the fermentation range that you’re looking to achieve. Since I knew my house would be cold enough, this setup only accounts for heating the fermenter. If your location is too hot (like my garage would have been), you may want to look into a way to chill the fermenter. The SCOBY that I got from The Kombucha Company suggest fermentation temps from 70-84 so I set my controller at 78 with a +/- 2 differential meaning that it would turn on when the temp hit 78 and it would turn off at 80. If you choose to use the MTSs controller, these are two advanced settings to look for: LS = Low Set Point / D = Differential
That’s it, pretty simple, right? I’ve got a batch brewing right now and will update this as it goes.
Heating Kombucha from the Bottom
While I was writing this post, I happened to get an email from someone asking about kombucha brewing in stainless, lids and cloth for breathability and when I happened to mention this post I was writing, I got the following response:
I’ve heard that heating from the bottom of the fermentation tank leads to excess yeast production and isn’t optimal… not sure if there is any real science behind this but that’s what i’ve heard from old timey kombucha people.
This made me curious. I had done one batch in a ceramic pot that was heated from the bottom and it didn’t seem to have a problem with excess yeast, in fact, I would say that visually, there was no more or less than usual. After doing a (minimal) amount of digging online, I came across a couple notes about heating from the bottom, with no real definitive answers or conclusions. Those who do it that way don’t see any problem with it.
In my opinion, heating from the bottom would provide the most benefit. You’ve heard the saying “heat rises”, haven’t you? As liquids cool, they become more dense and will fall to the bottom of the vessel, so as the liquid is heated, it becomes less dense, causing it to rise. This will create ‘currents’ inside the fermenter giving a relatively even temperature throughout.
In any case, I’ll try to follow up with an update to this at some point, or if you have any questions, feel free to ask in the comment section below.
Thanks for reading and happy brewing!