Airlock Bubble Counter

This project turned out to be more of a challenge than I was expecting. Although putting together the various circuits and software to get things working during the breadboarding steps was quick and straightforward, producing final drawings, code and documentation for this website proved to be a mammoth undertaking. To help address this, I decided to publish this project in the form of installments and so you will see the project grow within these pages as things progress.

If the page you’re looking for is not there yet – don’t worry it should be there shortly.

Ok, ’nuff said, now on with the project.

Homebrewers usually use some form of air lock on their fermentation vessels to allow the generated carbon dioxide to escape and to keep air out. During fermentation, the brewer can watch or even count the bubbles of carbon dioxide as they pass through the air lock over a given time. This can give a good indication as to the health of the yeast and to monitor fermentation progress – especially as it gets close to finishing. Some brewers claim that fermentation will continue even after the bubbles have stopped. I think the truth is that the bubbles are then so slow in coming that they think they’ve stopped, or the gas is leaking out somewhere. If the fermentation is very slow, then counting these bubbles over a now long period can be very tedious – especially if the fermentation vessel is in a cold, dark place and you’re already thirsty.

Wouldn’t it be nice if this counting could be made automatically and when we’re not even present? We can use a suitable sensor and an MCU device to do this for us and keep a total record of all the bubbles produced over the course of the whole fermentation and we should then be able to tell when fermentation has actually finished.

Another aspect of counting and timing bubbles is that we might be able to monitor the volume of carbon dioxide being produced and use this information to predict alcohol production. This idea was quickly dismissed as the size of the bubbles seemed to vary a lot and what’s the volume of a bubble anyway?

I thought that building an automatic bubble counter might be a new idea – but like just about every other good idea, it wasn’t! A German company, Speidal, has developed a bubble counter to work with their own air locks, to count the bubbles during fermentation. You can get details of this “GÄRSPUNDmobil” product at: https://shop.speidels-braumeister.de/en/accessories/fermenting/gaerspundmobil. It’s not cheap, but if you want this sort of this thing with instant gratification, global access and probable reliability, this could be for you. However, if you’re a true cheapskate and anarchist, read on – this one will cost you just a few dollars.

Another option would be a device from a company called PLAATO: https://plaato.io/products/plaato-airlock. This is a very clever device. Not only does the product count bubbles but the developers have managed to standardize the size of the the bubbles. This means that the volume of generated carbon dioxide can be measured. The amount of alcohol produced is proportional to the volume of carbon dioxide produced and so this can be reported by this device, too. It also measures fermentation temperature and has wireless capabilities for remote monitoring. I was fortunate to be able to meet the developers at HomeBrewCon 2019 – these guys totally know what they are doing.  

There’s also been several diy efforts to make a bubble counter…

Somebody called Nate put together an interesting article 11 years ago at: https://www.sparkfun.com/tutorials/131

A newer version of a bubble counter was posted by Waldi at: https://www.instructables.com/Bubble-Catcher-Part-1-of-2/. Again, he used a photo-interrupter sensor to detect the passage of bubbles through a s-shaped airlock.

Here’s a another from Matthew McGowan: https://www.youtube.com/watch?v =XnkTrGFeNJI&feature=emb_logo

And, another by Tronominon: https://www.thethingsnetwork.org/forum/t/beer-fermentation-bubble-counter-heltec-esp32-node-red-thingsboard/19930

This device from Kbaggan looks interesting although I couldn’t access any details from the posted links because of subscription requirements. It looks like it’s using some sort of microphone to ‘listen’ to the airlock. https://www.homebrewtalk.com/threads/bubbler-logger-a-fermentation-logger-measusing-co2-sound-bubbles-to-calculate-sg.665988/

Here are a few other links that are related to bubble counting…

http://brew.ellams.com/fermentation-bubble-counter/

https://jplattel.nl/post/2018-01-07-creating-smart-bubble-counter-fermentation-tracking/

https://www.programmingelectronics.com/homebrewing-arduino-student-project/ 

https://imgur.com/gallery/U3e4S 

So, far from being a new idea, there are many options for bubble counters out there for interested brewers. So why should I even bother to put together a new project to build a bubble counter?

I think it would be fair to say that anyone wanting a bubble counter has two options: either pay money up front for a commercial product or try to reproduce the one of the homemade devices. A commercial device should look nice and should work reliably – but it will come at significant cost. The construction details for many of the homemade devices are rather rudimentary and the performance and appearance might be lacking. However a homemade device will be cheap and it can be easy to add new features to it.

My intent with projects like this is to provide full construction and operation details so that a smart looking and full-featured bubble counter can be produced.

As mentioned earlier in this section, I will be publishing this project in installments if only to give myself some illusion of progress. The project will be structured as follows:

• Introduction – you’re reading it now!
• Concept – overview of device and how it works
• Breadboard system – components mounted on a solderless breadboard to enable initial testing and to develop the bubble detection algorithm.
• Anatomy of an airlock bubble – interpretation of the signal generated by the optical sensor and development of an algorithm to reliably detect and count a bubble passing through an airlock
• Fully-featured bubble counter – concept, features, build and operational instructions.

These sections will occupy several pages on this website. They can be accessed sequentially by the page buttons at the end of each page or from the Contents menu at the top of each page.

A Comments box will be included at the end of each page for you to provide feedback (if you wish).

Note that this is a fairly advanced project but it should be possible for anyone who knows which end to hold a soldering iron to successfully complete. I found that the most difficult and tedious part of this project was to design and build a suitable enclosure. There is nothing expensive needed to build this airlock bubble counter (apart from a computer and possibly a 3D printer) and the whole device should cost no more than about $25. It would make a great present for a really close friend.

There is plenty of scope for makers to modify and adapt the design for their own evil purposes – if you do, please let us know by using the Comments box.

Good luck! 

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