Fermenting your homebrew at the right temperature is one of the critical factors in making good beer. Let the temperature get out of whack, and the yeast will punish you.
Since 95% of homebrewed beers are ales, temperature control is usually not an issue. Ales are perfectly fine fermenting at room temperature between 70-75 degrees F. It’s when you use lager yeast that things get tricky. These Eskimos like to work between 50-55F. That’s tough for a homebrewer without specialized equipment.
My latest homebrew is a Kolsch, which uses an unusual blend of ale and lager yeast (White Labs WLP080). It still requires lower temperatures, 65-70F, but that is much more manageable than 50-55F. I aimed for 63-65F because reviews said that the strain works best in that range.
Enter the Swamp Cooler
A swamp cooler is a crude fermentation chamber used to keep lower temperatures. It is usually made out of a cooler, bin, or other large container. The idea is that you put your fermenter into the container with cool water and use ice packs to maintain low temperatures.
As you can see in the picture below, my swamp cooler consisted of:
- Water filled to the beer level
- A plastic tub typically used for holding beer cans or a keg
- A t-shirt (towel can also be used)
- A combination of frozen water bottles, small ice packs (the kind used for ankle sprains), and ice filled Ziploc bags
I kept the shirt wet for the evaporative cooling effect. The picture below shows the inside of my set up:
The Results
The goal was to rotate the frozen objects in and out to try to maintain my temperature range between 63-65F. There were 2 main challenges with this:
- Getting the temperature low enough
- Consistency and preventing large fluctuations
#2 was my biggest concern. It’s often said that preventing wild temperature fluctuations is more important than the temperature itself. Making it more difficult was the fact that I was out of the house 8-9 hours per day with no Keebler Elves to manage my swamp cooler.
Here are the readings for the first 2 1/2 days. WARNING: DO NOT LET YOUR KIDS LEARN CHARTING FROM THIS P.O.S.! The time axis is not to scale and I mainly took readings on the high side. Still, it is telling…
At first I was worried that I wouldn’t be able to get the temperature low enough. 2 water bottles brought it down to 66F from room temperature (72F), but it went no lower. Frustrated, I replaced the 2 water bottles with 2 new ones and 2 Ziploc bags.
Oops! 52 degrees! At least I knew it could go low enough…
Once I got the routine down it wasn’t hard to keep the temperature between 60-65F. The beer is 1 1/2 weeks in and I’ve maintained that range the entire time. Not the ideal consistency, but acceptable.
Some notes:
- Once the temperature reached 62F it could be maintained by adding 1 frozen water bottle every 3-4 hours when it hit 65F.
- It was much easier to maintain the temperature in the evenings because I was around the house and could use the small ice packs for minor adjustments. It was overnight and during the day that were trickier, and when I got more fluctuation.
- Many homebrewers recommend aiming a fan directly at the carboy to help with cooling. I tried this and didn’t see any difference. I think it was because my carboy was mostly covered by the tub and only a small bit of air hit the top of it.
Final Notes
If you (or someone else) can be around enough to rotate ice packs, then this is a great way to do cooler fermentations. Just be forewarned that anything in the 50-60F range will require very close attention. I actually think this tub type arrangement is a better strategy for fermenting ales between 65-70F. This is much easier to maintain and will yield cleaner tasting beer (less esters) than one fermented at room temperature or above.
Will I do it again? Damn right.
But I have big plans for upgrading the next one. (Hint: it involves a cooler)
Stay tuned for Swamp Cooler – Part Duex.
Have you tried anything like a swamp cooler to lower your fermentation temperature?
Related Posts:
Did You Enjoy This Post?
Subscribe to get free updates. Note this is not the newsletter, but blog updates only.
{ 15 comments… read them below or add one }
I live in hot and muggy South Florida, so it’s a challenge to even keep ales fermenting in the proper temperature range (without spending my entire pay check on air conditioning). I use the swamp cooler idea on every homebrew. I have 18 frozen bottles of water in my freezer, and I rotate them 6 at a time every 8 hours. It does a real good job keeping it between 70-75 degrees.
I had the opposite problem with my Saison…couldn’t keep the temp high enough. Ended up sitting it in 90 degree water for a day and then dresing it up in my winter coat so that the exothermic reactions would keep the beast at 85 degrees.
For lagering, I’m blessed with an old coal cellar in my basement that keeps lager cool even in the summer.
.-= nate´s last blog ..I Drink Beer & It Makes Me Happy =-.
@Adam 18 water bottles! Jesus I don’t think I could keep up with that. What is your swamp cooler like? Do you use the tub like I do or have a different (better) set up?
@Nate I feel like this is the story of Goldilocks and the Three Beers. Adam’s is too hot, yours is too cold, and mine is right in the middle (but all over the place) lol. I’d kill for your cellar. Keep those Saisons warm and snug buddy.
Billy, I was wondering what you were talking about when I saw your tweet about this. Ahhh! It is a method I use in the summer. My basement is usually pretty consistent, but some of the yeast strains I’ve been using lately seem to be extremely exothermic. Raising the liquid temp up to 7 degrees above ambient temp (like my current Patersbier with Trappist High Gravity yeast)
I totally appreciate your leg work here with the graph, valuable knowledge. thanks for sharing.
.-= Peter at Simply Beer´s last blog ..Amanti Vino & Ruthies BBQ Beer Dinner Featuring Merchant du Vin =-.
Just to add a little to the great article…I have had great success using an aquarium heater in a similar fashion. I keep my carboys in my garage where it is usually in the high 50′s. The aquarium heater will easily keep the fermentation going at 68 degrees. Sometime I will even throw in frozen water bottles to keep it from getting too warm….but usually it’s not needed.
@Peter Yea when I first heard the name I was pretty confused lol. Ah yea I remember that insane Trappist yeast you had. Sure makes it hard to maintain temps with something like that. Glad you liked the post and thanks for stopping by!
@Al Thanks for sharing that Al. I actually read about that technique recently and it is a great idea. You can probably find those heaters cheap online too. I will give that one a shot in the winter.
@Billy Broas that is the exact same beer I was just telling you about on twitter, the Belgian that @Peter has – it shocked me too. I had my house at 72 but it was reading at 78 in the carboy.
I’m trying the mixed swamp cooler right now. Don’t think I’ll have to add much ice to it to keep it around 72 but got the temp down from 78 to 73 in the Carboy. Without hopefully having to run my AC all the time!
I have a fan on it as well.
Will just have to see how to accommodate it. It was 97 here and currently 89 but feels like 96.
The next two are the chocolate stout and then an IPA (Sinistral Warrior).
@Thile Yea it sounds like the yeast really heats things up with its exothermic reactions. The swamp cooler is a great way to buffer the temp swings from those strains. Also much cheaper than running your AC full blast. Stop back in and let us know how the brews turn out!
I’ll let you know for sure.
Interesting thing happened. The head had dropped down some so I put on the fermentation lock. Well after I’ve had the temp stabalized at 72 (bath) / 73 (carboy); it foamed back up and was coming into the lock. So I reattached the blowoff hose and will see how it goes for a bit more..
I use this approach for all of my home brews. Being in south Florida it gets hot, so this technique is a great way to keep the temperature down. I also fill the tub with water to help keep the temperature constant. The only thing is I need to change the towel often because after the towel sits in the water for a couple of weeks, it smells terrible.
Cheers!
@Thile Wow that is pretty unusual. The krausen dropped and then came back up. Those things are pretty unpredictable though. I wonder if it had anything to do with the pressure from putting the airlock back on?
@Chalie It seems like this technique is pretty standard in the hotter states. Yea I’d imagine a few week old wet towel wouldn’t smell so hot. Do you use an open tub like I do? I can’t wait to try the next version of the cooler. I think it will be much better.
Cool, I did not, thinking about it, but I’ll certainly try.
I was just wondering what you are using to keep track of the temperature ? Do you just have the sticker thermometer on the side of your carboy ? Also, when you say fill the water to beer level, do you just mean the water should be up to where beer is in the carboy ?
Thanks for the help. I am trying to figure out a way to keep the temp down between 66-68. Our place is a constant 75 because my wife is always cold.
@Jon Hey Jon, you’re correct, I have one of those sticker thermometers on my carboy. It is at the 5 gallon mark, and I fill the tub with water so that it is just below the thermometer (you don’t want to submerge it). So by beer level, I actually mean just below beer level to give the thermometer room.
I think the swamp cooler is a great option for you. If you haven’t seen it yet, also check out my more recent post on fermentation chambers: http://billybrew.com/fermentation-chamber-options. There is a more advanced version of the swamp cooler in there that keeps more consistent temperatures.
My girlfriend is always cold too. I’ve managed to convince her to keep the house at 68, but that requires me putting a blanket on her whenever she sits down. I don’t think this is going to last throughout the winter…
Thanks for the reply. I appreciate it. Loving the site. I am off to the homebrew store.
{ 2 trackbacks }