first attempt at swamp cooling

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beerluvva

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Attempting the swamp-cooler method to control fermentation temperature, I've logged some temperatures throughout the lag & primary phases, and I'd like to know if they are in the ballpark.

Below is a picture of my cooler.
cooler.jpg

I usually brew 2.5-3 gallon batches in a typical 5 gal batch bucket. So in the photo, the fermenter is filled to 2.5 gallons, which is right about at the cooler water level. Cooler water is mixed with StarSan. Not easy to see in the photo, but I also have a t-shirt draped on one side of the fermenter for wicking/evaporation.

My ambient basement temp = 72-24 deg. F
Pitched at 63 deg F.

Before posting a lot of temp data, I'd like to ask a question about how to interpret the stick on thermometer. From the above photo, the thermometer is vertical, the 63-61 deg cells are right at cooler water level (and also at wort level, approximately). Some thermometer cells submerged in the cooler water, and some completely above wort and cooler water.

therm.jpg

After a few days of swapping bottles and taking readings at the water level, where 63-61 deg was indicated by the ferm, I noticed that a number of other cells on the thermometer were "lit", as shown above. I guess I expect this kind of thermometer to show a gradient in temperature if one exists (that is, more than one temperature, simultaneously), but now I question which values best represent the ferm temp ? In the photo, in case it is not clear, the values: 77,75...72,70,68...63, and 49,48,47, ... are lit up even if slightly.

When I logged ferm. temps., I was basically keying on the values at or above the cooler's water line, which in this case is the 63-61 deg mark. This also coincides with the top of my wort.

What my log seems to show is that the ferm. wanted to warm most aggressively in the first 24-36 hrs...seemed like bottle replacements were needed frequently to keep the ferm temp under 68-70...drops of new bottles would pull the temps back down to 63 or 61. After these 36 hours, ferm temp seemed to settle & be easily controlled around 63-61. But I see the other figures mentioned above too, so a little confused.

Thanks !
beerluvva
 
The temp that is most highlighted is where it's at but part of the problem is the strip got submerged, this will basically render the strip useless. Not immediately but you need a new one and place it horizontally above the average water line.

All in all though, good job, the beer will be great!
 
thanks...had thought the vertical strip was no good when I first started, but realized it just as I was dropping the fermenter into the cooler. :smack:. Will do a horizontal strip next time. In any case, hope I am fermenting cooler than I have in the past, I'm really interested to taste the difference.
 
Well the vertical strip is meant to have liquid in the bucket that is at least to the top of the strip. Submerging the bottom of the strip may have ruined that part. It sounds like you got useful temperatures from the middle, above the cooler water and below the wort level. Your observations of the temperature and the timing of the fermentation seem right. I think that it depends on what your temperatures on your batches prior to the cooler will determine if you will notice a difference. If they were not too hot you might not taste a difference. It is still in your best interests to use the cooler to control your fermentation temperatures.
 
Looks like you are using a muck bucket to put the fermenter in ..

I do the same in the winter...put the better bottle in the muck bucket, then set the aquarium heater for 68 ... works like a champ
 
Use external temp monitoring, there's a nice thread on HBT about the temperature differential between the water bath and the fermenter temp. Stick on thermometers are not reliable. In general I remember plastic buckets being 2-4F hotter inside than the water bath measures. Glass Carboys being within 1-2F, and Metal being very close to the water temp.
 
If you throw a big towel over everything, you might get a few degrees lower. I did after my LHBS gave me the tip. I didn't think it'd make a big difference, but it did!

Also, I suggest ditching the ice packs and grabbing a few cheapo water bottles to use instead. But just my preference after playing around with it a bit. I use 1 liter water bottles i got at the .99 Store.
 
If you really want to keep your temp steady try using a ice chest. I can even ferment a lager in the middle of summer in a ice chest. And with little effort hold my temp at 49 steady. In the winter i just have to change out the frozen water bottles twice a day. Since the ice chest/cooler is insulated it just makes it that much easier!!
 
kh54s10 said:
... I think that it depends on what your temperatures on your batches prior to the cooler will determine if you will notice a difference. If they were not too hot you might not taste a difference. It is still in your best interests to use the cooler to control your fermentation temperatures.

I guess in my past brews I committed the dual sins of pitching too hot and using no temp control at all in a 72F ambient room. I've pitched as high as 78 without any control...this is with wyeast 1056. Hoping now with better pitch temp and some effort to manage temp during ferm. I'll notice some difference straight away.
 
swamp cooling means evaporative cooling, so yours would only be a swamp cooler if you had a towel or something expanding the surface area by wicking the water up, to where it could be evaporated off, usually accelerated by a fan blowing over it; the energy required to turn water from liquid to vapor at the same temperature is relatively high, it is that energy expenditure that cools the system. (not trying to be pedantic, that's just what swamp cooling means). your cooling appears to come from the ice blocks, so you are cooling by heat conductance.
 
You can't really see it in the photo, but I am attempting the evaporative cooling with a t-shirt that is draped top to bottom on the back half of the fermenter, the side facing away from the photo. I did it that way only so I could easily read the thermometer.

Not using the fan though, was just relying on regular evaporation.
 
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