[syncopadence]

It seems the popular opinion has been to drop it down to the 33° area as fast as possible, but I've heard recently that this kind of temperature shock can have just as bad of an effect as it does at the beginning of fermentation. Anyone ever experiment with this? Any science to prove/disprove?

[davidgzach]

Crash away.  Does not affect anything.....

Dave

[kramerog]

Some people don't "crash." Rather they drop the temperature slowly to avoid or reduce oxygen being sucked through the airlock.  I crash because I use my kegerator for cooling.

[Steve Ruch]

Some people don't "crash." Rather they drop the temperature slowly to avoid or reduce oxygen being sucked through the airlock.  I crash because I use my kegerator for cooling.

Dropping the temperature shouldn't suck any air in through the airlock, water expands as it cools which is why ice floats. I'd think you would more likely get air sucked in when the wort warms up.

[syncopadence]

Hmm I have to agree with the air being sucked in. Ice floats because it's less dense than water. Going from warm to cold air causes a vacuum. Think about a wooden door in summer as opposed to winter. Warm, humid air causes the door to expand, which sometimes causes it to jam up. My question is more about the effects of crashing on off flavors.

[HoosierBrew]

1/  IF you're at FG, crash away. I crash lagers (that are @ FG) as well, with no negatives.

2/ As for suck back, crash in a keg with head pressure and there is no suck back.



Edit for sorry spelling.

[davidgzach]

I had the sucking air and nasty blow off water back in the fermenter problem with my lagers.  Never could figure out why even when I slow cooled.

Now I simply empty the blow off container when ready to crash, wash, sanitize and replace without water but with a rag drenched in star san over the tubes.  Never a problem again....

And +1 to Hoosier for making sure you are at FG.  If you are making a lager I always crank it up to 65F for a couple of days to burn it out.  I know lager makers, not necessary if you pitched enough yeast, but I like it.

Man, my first posts in like 2 years.....

Dave

[HoosierBrew]

Good to see ya back, Dave !

[Joe Sr.]

If it's been two years  getting old.

As far as crashing I usuly just do it in the keg. Blow out the first pint or so and bobs your uncle.


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[narvin]

Some people don't "crash." Rather they drop the temperature slowly to avoid or reduce oxygen being sucked through the airlock.  I crash because I use my kegerator for cooling.

Dropping the temperature shouldn't suck any air in through the airlock, water expands as it cools which is why ice floats. I'd think you would more likely get air sucked in when the wort warms up.

Water is most dense at 4c, so the majority of your crashing is going to increase density and decrease volume.

[davidgzach]

If it's been two years  getting old.
 
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True dat....

[jtoots]

i go with about 5 degree increments just to give the refrigeration system a break

[Todd H.]

Dropping the temperature shouldn't suck any air in through the airlock, water expands as it cools which is why ice floats. I'd think you would more likely get air sucked in when the wort warms up.
[/quote]

Water only expands as it cools between 0C and 4C.  Above 4C, it contracts as it cools.  Ice floats because it is less dense than water (i.e. you were right on that, it "expands").
Irrelevant though.  Gases also contract when cooled.  This creates a vacuum in the carboy, causing suck-back or whatever you want to call it in the airlock.

[denny]

It seems the popular opinion has been to drop it down to the 33° area as fast as possible, but I've heard recently that this kind of temperature shock can have just as bad of an effect as it does at the beginning of fermentation. Anyone ever experiment with this? Any science to prove/disprove?

What's gonna be shocked by the fast drop?  As long as fermentation is finished, there's no need to worry about yeast shock.  And I can't think of anything else that would be affected.

[blatz]

I step down just because I don't like to 'shock' my fermenting fridges - dropping from 68 to 35 all at once tends to keep the compressor on too long.