Homebrew notes – Batch 2. Australian Pale Ale

In which I build a cheap fermenter cooler, program a Raspberry Pi to send temperature sensor readings to a database for tracking remotely, and forget to track starting gravity once again on a batch of Australian Pale Ale extract homebrew.

It seems the first few batches will be more focused on tools than ingredients, as I’m skipping the whole brew phase by just pitching into extract. I started on this second batch the day I bottled the first. I’d like to improve as quickly as possible, however given how little I drink, I’m thinking I may need to slow down. I now have the equivalent of three cartons lying around. Hmm.

Mangrove Jacks Australian Pale Ale packaging

An Australian Pale Ale LME kit from Mangrove Jacks. The brew process is still extremely simple as with the first batch. I’m looking to focus on better preparation and fermentation control this time, along with figuring out how to track how things are going a little better.

1. Aims

  1. Improve on fermentation environment for lower and more consistent temperatures.
  2. Create a system to track temperatures over time.
  3. Figure out how to dry hop with minimal fuss.
  4. Clean and sanitise sufficiently before brewing to avoid infection

2. Tools

I purchased a few new tools to complete this brew. Firstly a small permeable hop bag, which will keep the bulk of any hops together to keep them from clouding up the beer when I dry hop. I grabbed some marbles from a dollar store to weigh the hop bag down as well, as it tends to float which means the aroma doesn’t infuse as efficiently. I also bought an oversized bucket to use as a shallow insulating water bath for the fermenter.

Most of my effort this time around was spent coming up with ways to control what I’m doing. Some of these efforts had more merit than others.

Creating a fermenter esky

Its hot in Brisbane. My current swamp cooler solution didn’t really work. Having a USB fan close to a water source was probably a fire hazard and I was occupying the laundry sink for weeks at a time while its needed for other things. A swamp cooler can only do so much when working as an evaporative cooler in close to 100% humidity. Insulation and cold-packs seem best and I need to insulate a large ~30l fermenter so a standard esky won’t do unless I want to spend hundreds on a giant one.

Polystyrene foam insulation board, commonly used for under-concrete insulation in housing, is rigid and lightweight enough to create a freestanding structure. It’s also not terribly expensive and with a little duct tape around the edges, I was able to construct something that contained the full height with room to spare.

I constructed it so the front opening flipped down a little like the back of a ute tray. This meant I could open the container to check on things without the cool air entirely draining out.

All in all, the container cost about $60, covering three lengths of board from bunnings and a couple of rolls of cloth tape. The above photo shows the bucket I picked up at the same size to allow me to partially submerge the fermenter in water to insulate and stabilise temperature. It also shows the few reusable cooling blocks I picked up to switch out of both the cooling bath and the surrounding container for shorter and longer term cooling.

Creating a temperature monitor

The thermal strip on the side of the fermenter gives a good-enough temperature reading, but I have to go to the garage to check on it throughout the day if I want to make sure its where it should be. It’d be much better if I could read the temperature wherever I was.

Ambient temperatures hit highs of around 34C here in the summer and even with my little esky built, I need to drop the temperature in the fermenter to around 21C somehow without going lower than atound 18C. I don’t have any active refrigeration going on so I need to track how the temperature changes over the course of a day to throw in more or less ice packs accordingly. So I need a remotely accessible temperature sensor, preferably with the ability to chart the rate of change over time.

I purchased some DS18B20 sensors from RS Electronics, along with a resistor to bridge between the data and power lines to make the signal readable. I soldered together a bunch of them to attach to the GPIO of a Raspberry Pi 3 I had lying around collecting dust. The design of the sensors is pretty neat. You can connect them all to a single line and the reading that each send through comes with a unique identifier to allow you to tell each sensor’s readings apart. Here they are soldered together to the one ground/power/data stream.

Then I taped the lot to the side of the esky. The wifi transmitter on the Pi was within range of the wifi at home, meaning everything could just get pushed straight to the site.

Each thermal sensor carries its own unique identifier, which I marked out with masking tape to differentiate between readings taken outside the container, inside the container and against the fermenter.

I then followed this guide to write a python script to take readings every ten minutes using the sensor and send them to a database created on my website. I then used this guide to create a small javascript app to read from the database and transcribe the last day’s readings into a legible JSON format and contain that in a file. This file was then read using php embedded in a page which displayed the readings using chart.js. The resulting page could be loaded anywhere to display the current temperature as well as tracking the temperature since midnight.

Typical set of readings tracked over time. I really didnt need this many data points.

Using this meant I was able to see when my cooling methods were becoming ineffective (mid-afternoon). This in turn meant I started overshooting in the morning with extra ice packs in the surrounding pool as well as sitting in the insulated container. The result was a fairly steady temperature that oscillated within close to the ideal range most of the time. I didn’t have to rely on the colour coded stick-on thermometer and only needed to pop out to tend to things when it was actually necessary.

The sensor used to read the fermenter temperature directly was attached to the outside of the fermentation vessel using tape, with a layer of insulation placed over the top to prevent contaminating the reading with the ambient temperature. The goal was originally to also track ambient temperature inside and outside the container to examine efficiency in insulation but I think this might be overkill in hindsight. This is probably good enough until I eventually invest in a small fermentation fridge, at which point tracking will no longer be so important. I don’t imagine beer I’m making before then will be good enough to be affected by any uncertainties in readings. Even if they are, fat lot I can do with the blunt solution of dropping in ice packs.

3. Ingredients:

Mangrove Jacks LME kit — Australian Pale Ale

Galaxy and Ella hops for dry hopping. I found these included in a single room temperature bag as part of the LME kit.

Light dried malt from Brewers Choice

4. Technique

Pitched: February 12

OG: unknown

Dry hopped: March 4 at SG 1.012

Hop variety: Galaxy and Ella

Bottled: March 11

FG: 1.012


I followed mostly the same method as for the first batch. This includes forgetting to take a starting gravity reading. I realised I’d messed up after a couple of days, however by this stage it was too late as most fermentation occurs right after the yeast sets up shop… So it’s another mystery brew.


I managed to get the yeast added within 30 minutes of boiling and aerating, as the temperature dropped to 26C fairly quickly

Dry hopping

I dry hopped! You can do this by just chucking the hop pellets in once fermentation is pretty-much done, however I went and got a cheap mesh hop bag, which I tied up with the hops inside. I threw in ten or so glass marbles to help weigh the bag down, however this wasn’t enough somehow, so I’ll double the amount next time around. The bag meant that the hops don’t run the risk of blocking up the tap on bottling day. It also means fewer little green bits floating around in the finished beer.

Breaking shit

I smashed the shit out of my hydrometer. Fantastic. I smashed the shit out of it on a day when I was 90% certain I was safe to bottle. Fantasticker. We took a trip to the homebrew shop, only to be told they were out of stock. Fantasticker still.

I ordered one online and left the fermenter to sit while I waited. I guess there wasn’t any rush. I believed that leaving it for longer could only serve to let the yeast clear things up a bit more and it’s not like I’m running out of beer from the first batch. I realised that this also meant I had time to throw in some finings, which I did a few days after the hops but a few days before bottling. Finings are made of pork gelatine and I have vegan friends and family, so this realisation means I probably won’t use the stuff after this round.


I bottled on Saturday 11 March, a good four weeks after starting on February 12. I’d have bottled on week three if not for the hydrometer issue. Turns out this was a mistake

 5. Result

Oh hell. It tasts awful. Far, far too strong. Its like I left a tea bag sitting in a boiling kettle for four hours. Might have been an infection. Might have been an effect of leaving the thing sitting for ages before bottling. Maybe a combination or one leading to the other. I’ll see how much of it I can get through but once I run out of bottles for future batches I might start sacrificing a bit of it down the drain.

6. Lessons learned

  1. Plan the development of your loadout
  2. Gelatine is the primary if not only component in finings. There are other ways to clear beer in a more vegan friendly way.
  3. You don’t need  a billion temperature sensors. One will do. Could have skipped this and just gone straight to a fridge for a bit more cash. Your time isn’t worth that amount of screwing around.
  4. Don’t leave it sitting in the fermenter for ages. It matters.