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-   -   drop in fermentation temp bad?? (http://www.homebrewtalk.com/f39/drop-fermentation-temp-bad-94087/)

bell0347 12-22-2008 04:16 AM

drop in fermentation temp bad??
 
I am a paramedic and being such I work a jacked up schedule. Between work and school and other junk I don't make it home too often. Anyway, when I ferment I stick my bucket in my spare bathroom tub and fill it up. The temp of the water hovers around 68F. This wonderful Texas weather drops like 40degrees one day and is back up in the 70's the next. I am not at home to monitor the temp. closely so the best I can do is hope the water mitigates the temp. change some. I know a rise in temp. can lead to some off flavors but is gentle drop and then rise back to original fermentation temp gonna have any negative effects?

I deally, I will be building a fermentation cab as soon as I get moved, next month maybe!

BrianP 12-22-2008 04:34 AM

Yeast interpret a sudden drop in temperature as a signal to prepare for survival. Many strains will drop out of suspension and stop fermenting. If they do this you need to try to restart the fermentation by making a small starter with new yeast and pitching this actively-fermenting wort into your 'stuck' wort.

Your best bet is to prevent a stuck fermentation is to place your carboy or bucket someplace in your house with the most consistent temperature, such as inside a closet, away from an external wall, etc. Putting it inside a tub of water, like you're doing, is also a good idea since it slows down the temperature swings.

Another option is to use a heat wrap and a temperature controller to ensure that the temp doesn't drop. Basically the controller will turn on a heating pad as the temp drops, then turns it off when not needed to keep the wort temp fairly stable.

bell0347 12-22-2008 03:17 PM

I thought about the heating pad thing and the temp controller. I might try that next time. I also have an aquarium heater for a 75 gallon tank I used to use. I thought I could suctino cup that to the tub and let it settle the temp. out. Hmmm........ Anyway, so just raising the temperature back to the orighinal ferm. temp won't kick the yeast back in gear? I will check activity and gravity tomorrow when I get home and repitch I guess if I need. I used Safale 04 for an irish red, I have a pack of Safale 05 in the fridge, can I use that even though a different strain, wont make some crazy off flavor or some crazy yeast battle to the death in the wort?

desertbronze 12-22-2008 03:21 PM

Yeast don't like rapid changes in temperature, in my experience. You're on the right track with the water bath. That will eliminate any big swings in temperature. The aquarium heater is a good idea to prevent the water from getting too cold.

When my fermentations are near finished, I let the beer warm up slowly (1 to 2 degrees per day) until it gets to room temperature (75 F.) in my basement. That seems to help the yeast finish their job.


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