Ferm. Temperature with Water Bath

[PittsburghBrewer]

I've been controlling fermentation temperatures by submerging my fermentation buckets in a water bath in a 60 qt. Igloo cooler. I typically fill the cooler so that the water level matches the top of the beer in the bucket. I then add reusable ice packs to manage the water temperature.

I don't have a good way to determine the temperature inside the bucket. For other people who use a water bath: any insight on how close the internal fermentation temperature is to the temperature of the water?

 

[catdaddy66]

I have used a thermometer in the swamp cooler to measure the water's ambient temp and generally add 5° to it for the temp of fermentation in the primary. It is a good guess but not wholly accurate.

Even this crude approximation has helped my beers improve.

 

[ChelisHubby]

I do something similar but with a carboy and a 70 quart cooler. I have found that the water temp is only 1 degree cooler than the beer temp when the fermentation is ripping hard. By insulating the top of the cooler I have to change maybe 25% of the ice bottles that I would need for the same effect of a swamp cooler.

 

[Sadu]

You can buy one of these...
https://www.aliexpress.com/item/Dig..._8&btsid=9a499bec-5bcb-4664-b5ad-4ae08e6ed235

and a 3 piece airlock...
https://www.aliexpress.com/item/Air..._8&btsid=fabf0f5a-c311-4e52-9fc5-44d239da832e

Then you can bend the wire around inside the airlock and have it hanging in the beer. Gives you a good reading of what the actual beer temperature is. My experience is that this cheap gear doesn't last forever, but then I was using them for mashing as well as fermenting and I don't think the higher temps do good things for the cheap probes.

If you want to go next-level then get a STC-1000 controller (there is bit of simple wiring required)...
https://www.aliexpress.com/item/STC..._8&btsid=203febbc-8a7b-47f7-be29-d93f4e3a1eb6

And an aquarium heater...
https://www.aliexpress.com/item/Bes..._8&btsid=753a23e1-8c06-4bac-b314-f26e8a0f57c7

and that way the temperatures will not go below what you set the controller to if you add too much ice. I found this handy since it gets cold at night and ales would end up at 14c / 57f without this. That aquarium heater actually has a thermostat built in, I don't use it, but you could skip the STC-1000 and use the aquarium heater thermostat to decide when to start heating.

All of the above is not expensive at all.

 

[ncbrewer]

I put a fermometer at the 4.5 gallon mark - bottom is around 4 gallons. Water bath is filled to around 3 - 3.5 gallons. This works pretty well. And I've found that the difference between the water bath and the beer temp isn't constant. During the lag phase I see greater difference. I've done a search on this but can't find whether temperature rise during lag phase is what the science predicts. I'll be getting the book Yeast soon - maybe I'll find out then.

 

[Brew_G]

In general, the temperature of the water bath will be very close to the temp of the fermenting beer/wort. The walls of any fermenter aren't good enough insulators to keep the temps of liquid inside and outside the walls very different.

I use a 30L Speidel that I put in an 18-gallon bucket filled with water up to the level of the beer inside. I use an aquarium heater to keep the temp up when it's chilly and occasionally use ice bottles to bring it down when it's cold. I use the temp of the water as a gauge for the fermentation temps and don't have any issues.

 

[Chrisbrewbeers]

3-4 inches water is enough IME, I use a stick on thermostrip. I have never seen a benefit to having more water in there. It just seems harder to control when more.

 

[ChelisHubby]

3-4 inches water is enough IME, I use a stick on thermostrip. I have never seen a benefit to having more water in there. It just seems harder to control when more.

THis is correct if using a swamp cooler, Using a water bath will asorb more heat than the cooler and will cool the entire surface of the carboy which will result in slower tempature changes. My water bath holds 7 gallons of water and that water asorbs the heat much better than the swamp cooler with 2 or three gallons. Maybe asorbs is not the proper spelling or descriptor but my temps don't move but maybe half of what they did when I put a wet T shirt over the carboy. Water wicks away heat much better than air ever thought of. I still think that a conical that has a jacket for cooling and heating is the best solution.

 

[GPP33]

THis is correct if using a swamp cooler, Using a water bath will asorb more heat than the cooler and will cool the entire surface of the carboy which will result in slower tempature changes. My water bath holds 7 gallons of water and that water asorbs the heat much better than the swamp cooler with 2 or three gallons. Maybe asorbs is not the proper spelling or descriptor but my temps don't move but maybe half of what they did when I put a wet T shirt over the carboy. Water wicks away heat much better than air ever thought of. I still think that a conical that has a jacket for cooling and heating is the best solution.

I put a bunch in mine too, not sure how much but I use a big plastic storage bin and fill it until it looks like it's about to pop. Water has a much higher thermal mass than air, the more water you put in the less your temp swings will be and the closer the temp of the beer and the bath will be.

 

[Brew_G]

I put a bunch in mine too, not sure how much but I use a big plastic storage bin and fill it until it looks like it's about to pop. Water has a much higher thermal mass than air, the more water you put in the less your temp swings will be and the closer the temp of the beer and the bath will be.

Couldn't have said it better myself.

 

[Maylar]

So if I wanted to cool a 6 gallon plastic ferment bucket, what sort of cooler would you guys recommend?

 

[PittsburghBrewer]

Thanks for all the replies, everyone. Much appreciated.

So if I wanted to cool a 6 gallon plastic ferment bucket, what sort of cooler would you guys recommend?

I've been using a 60 qt. rolling Igloo cooler to cool my 6.5 gallon bucket, and I've been very pleased so far. I cool the water to 64F with reusable ice packs the night before brew day, and I find the water is pretty close to that temp in the morning. My fermenter bucket wants to float when filled with 5 gallons of beer, so I weigh it down in the cooler using two 5-pound weights and an elastic exercise band.

The wheels make it easy to roll the cooler outside to dump the water when fermentation is complete. One issue is that I can't close the lid on the cooler when the bucket is in it. Even so, I haven't had much trouble maintaining the water temp. I want. I normally add ice packs no more than 3 times a day - before work, after work, and before bed. If you want to make a lid, I've seen pictures on other threads of a foam lid that Yooper made for a similar cooler.

 

[PittsburghBrewer]

I use an aquarium heater to keep the temp up when it's chilly and occasionally use ice bottles to bring it down when it's cold. I use the temp of the water as a gauge for the fermentation temps and don't have any issues.

What is the lowest temperature on your aquarium heater? I've been looking for one that can hold 64 or 65F, but it seems that most of them don't go below 68.

 

[Maylar]

Thanks for all the replies, everyone. Much appreciated.



I've been using a 60 qt. rolling Igloo cooler to cool my 6.5 gallon bucket, and I've been very pleased so far. I cool the water to 64F with reusable ice packs the night before brew day, and I find the water is pretty close to that temp in the morning. My fermenter bucket wants to float when filled with 5 gallons of beer, so I weigh it down in the cooler using two 5-pound weights and an elastic exercise band.

The wheels make it easy to roll the cooler outside to dump the water when fermentation is complete. One issue is that I can't close the lid on the cooler when the bucket is in it. Even so, I haven't had much trouble maintaining the water temp. I want. I normally add ice packs no more than 3 times a day - before work, after work, and before bed. If you want to make a lid, I've seen pictures on other threads of a foam lid that Yooper made for a similar cooler.

Right. Unfortunately, I'm making cider which requires 50-55F for a month or more. I think I'll go electric.

 

[Brew_G]

What is the lowest temperature on your aquarium heater? I've been looking for one that can hold 64 or 65F, but it seems that most of them don't go below 68.

I have the EHEIM Jäger 50w (https://www.amazon.com/dp/B003U82YEY/?tag=skimlinks_replacement-20), which runs from about 65F to 92F.

You can calibrate it, and I find that the temp can drift from time to time, but as long as you're checking it occasionally - especially before each new beer starts fermenting - you should be good to go.

It's a good price, and I like it enough that I just bought a second for my sour setup.

 

[ChelisHubby]

Thanks for all the replies, everyone. Much appreciated.



I've been using a 60 qt. rolling Igloo cooler to cool my 6.5 gallon bucket, and I've been very pleased so far. I cool the water to 64F with reusable ice packs the night before brew day, and I find the water is pretty close to that temp in the morning. My fermenter bucket wants to float when filled with 5 gallons of beer, so I weigh it down in the cooler using two 5-pound weights and an elastic exercise band.

The wheels make it easy to roll the cooler outside to dump the water when fermentation is complete. One issue is that I can't close the lid on the cooler when the bucket is in it. Even so, I haven't had much trouble maintaining the water temp. I want. I normally add ice packs no more than 3 times a day - before work, after work, and before bed. If you want to make a lid, I've seen pictures on other threads of a foam lid that Yooper made for a similar cooler.

I have done what Yooper did and it helps a lot !the foam is cheap and easy to work.

 

[GPP33]

What is the lowest temperature on your aquarium heater? I've been looking for one that can hold 64 or 65F, but it seems that most of them don't go below 68.

Mine only goes down to 68. I don't think most fishtank fish like anything below that.