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Old 07-05-2010, 06:50 PM   #1
Oct 2008
Bella Vista, AR
Posts: 41

I use an old chest freezer as a fermentation chamber.
I ferment at approximately 67 degrees.

After three weeks a large amount of mold and other "stuff0" starts to grow in my fermentation chamber.

It is a pain in the @$$ to clean up.

Is this normal?
What can I do to prevent it?
Will it impact my beer?

Yellow Dog Brewing Company
"Follow The Dog"

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Old 07-05-2010, 07:26 PM   #2
Jan 2008
Minneapolis, MN
Posts: 90
Liked 6 Times on 5 Posts

Chest freezers do not make good fermentation chambers, they are only marginally better for serving beer. The problem is they are not built to handle moisture the way a refrigerator is. Mold is a common problem, there is no way to keep it from happening. Some use Damprid but the best option is to get a refrigerator and use that.

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Old 07-05-2010, 07:45 PM   #3
Petey's Avatar
Oct 2006
Lawton, OK
Posts: 141

I've had the same issue in my fermentation fridge...try a tub or box of Baking soda. It doesn't stop it dead in its tracks for me but it takes a hell of alot longer for it to develop now.
Primary# 1: Dry Irish Stout
Primary# 2: Munich Helles

Secondary# 1:
Secondary # 2:

On Tap:
Robust Porter
White IPA
Dry Irish Stout

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Old 07-05-2010, 07:47 PM   #4
Dec 2009
Central PA
Posts: 197
Liked 2 Times on 1 Posts

I use mine as a fermentation chamber/lagering chamber. I have quite a few 'shop towels' that I line the bottom of the freezer w/. I change these out after every cycle of fermentation.

The other thing I do is take up all of the dead space w/ 1 gallon water jugs. This helps regulate the temperature better by acting as a sort of insulation thereby lessening the amount of time the freezer has to run.

Like goswell says, it is tough to avoid but by doing what I've outlined above I have not had a problem w/ mold, just quite a bit of moisture. One more thing, try to limit the amount of time that the freezer is open; this allows moisture to condense inside.

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Old 07-05-2010, 08:35 PM   #5
Dunerunner's Avatar
Jul 2010
Florence, OR
Posts: 795
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Originally Posted by Bert1097 View Post
Itake up all of the dead space w/ 1 gallon water jugs.
Keep a large thermal mass in the frige (as mentioned above), keep it dry. I hose my chest freezer down with Starsan every other week and wipe it dry.

Good Luck!

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Old 10-05-2012, 04:26 PM   #6
Oct 2012
Posts: 20

I Just set up a small fridge with the A419 controller and would like to avoid this problem.

What do you all think about using a few large silica gel packs; the kind used when you get items shipped to you?

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Old 10-05-2012, 04:31 PM   #7
Sep 2011
Robbinsdale, MN
Posts: 796
Liked 77 Times on 64 Posts

+1 to damprid. Had condensation pooling and sometimes mold in a fermentation chest freezer. Cleaned it up with starsan and put a bucket of damprid in and have't seen any condensation pooling since.

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Old 10-05-2012, 04:48 PM   #8
Senior Member
Hammy71's Avatar
Sep 2008
, Maryland, The Tax Me State
Posts: 5,906
Liked 534 Times on 407 Posts

When you don't need it to work as a fermentation chamber (after the first week of fermentation or when not in use), leave it open. Stagnant moist air is your worst enemy. I use a fridge for my chamber, when it doesn't have a carboy in it, I have it cracked open a good six inches. Mold be gone....

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Old 10-05-2012, 05:00 PM   #9
Nov 2011
Posts: 3,952
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Problem solved:

Eva-dry E-500 Renewable Wireless Mini Dehumidifer

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Old 10-05-2012, 05:31 PM   #10
Jul 2012
Austin, TX
Posts: 122
Liked 6 Times on 6 Posts

Non-clumping crystalline cat litter is a cheap source for the exact same silica crystal used in commercial desiccants. Make a bundle with a single layer of cheese cloth and toss it in to the bottom of your chest freezer.

Every few weeks, spray the inside of the freezer down with Starsan and you should be good to go. You can also help yourself by cleaning any wort drips off of the outside of your fermenter.

Reason: Corrected type of desiccant.

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