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First time cold crash

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NormanHurst

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The first brew in the fermentation fridge is coming to an end. I'm planning to cold crash as, I think, it will help clear the beer and also make racking into the bottling bucket a bit easier with less risk of transferring trub.

It's a Citra-led Pale Ale. Gravity stable at 1005.

The questions I have are:
1. Do I just turn the inkbird down low and crash fast - or should I be doing it gradually?

2. I bottle rather than keg. If I go too low for too long will I risk insufficient yeast for bottle carbonation?

3. How low do I go? I've read about chill haze. I normally drink Ales at around 10-12 C. I think crashing below this will be OK?

As ever, any help appreciated.

Norm
 

Buffers brewery

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I’m no expert but I just turn my fridge to 4 degrees C and leave it for 3 days. I decant into a primed King Keg which is my primary storage, then syphon off 4-6 bottles for my library. Condition PB and bottles at 12 degrees C. Had no problems with carbonation so far.
 

Banbeer

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Hi @NormanHurst the answers as follows:-

1. Turn the inkbird down to desired temp in one go

2. There will always be enough yeast to carb the beer as long as you are not silly with the temperatures

3. By the time the fridge has got to your target temperature (a day) at this time of year, you will need about two more days after that so 3 days really. Chill as low as your fridge can go as it will get rid of alot of debris.
 

Graz

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I just set mine to 1°C though the fridge never really gets there on the lowest setting, think the only way to achieve this is bypassing the fridges thermostat.

If I'm in a hurry I'll bottle / keg after 24 hours usually giving the fermenter a few taps / knocks around 12 hours in if I've dry hopped to encourage the hop debris to leave the surface. Typically though I'll keg / bottle after 48 hours. Never had issues with carbonation. I did once have a heavily dry hopped IPA that turned hazy which may have been due to chilling but didn't affect the taste so didn't bother me.
 

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I normally get clear beers at regular fridge temps (around 4c), the one time I cold crashed a. went at less than 1C for a week and it gave me a permeant chill haze.
 

cheeseyfeet

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Remember that cold crashing will cause a pressure drop in the fermenter which will suck in your airlock or blow off liquid!

After I set my fridge low I remove the blow off from my jar of starsan and use a bulldog clip to clamp it, hopefully minimising oxygen coming back in.
 

Buffers brewery

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Remember that cold crashing will cause a pressure drop in the fermenter which will suck in your airlock or blow off liquid!

After I set my fridge low I remove the blow off from my jar of starsan and use a bulldog clip to clamp it, hopefully minimising oxygen coming back in.
Interesting thought. I've always assumed at the end of fermentation there is a nice cloud of CO2 covering the beer surface and the small amount of air drawn into the top of the FV has no chance of contact over a 3 day period.
 

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Interesting thought. I've always assumed at the end of fermentation there is a nice cloud of CO2 covering the beer surface and the small amount of air drawn into the top of the FV has no chance of contact over a 3 day period.
Unfortunately that is a widely believed myth. Gases, even of different densities tend to mix (maybe serious different densities would be stay separate like an argon and helium mix). I don't remember where I read up on it to provide a source but I'm sure the CO2 blanket doesn't really exist. It is all to do with the velocity of the gas particles being greater than the effect of gravity.

I attach a gas bag filled with CO2 before cold crashing to avoid O2 getting in.
 

Petrolhead

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Only just part of this thread but my father-in-law, in his 80’s, spent most of his career with a well known brewery and enjoys telling the tale how the head brewer always wore a bowler hat and was always asked to take the VIP guests on their tour of the brewery.

His party trick was to take off his bowler hat and dip it in the ‘air’ above the open topped fermenting tun before asking a guest to smell the gas inside the bowler. On doing so the guest would inhale a lung full of CO2 and have a massive wobble or if the brewers were really luck keel over in a feint.
 

Buffers brewery

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Gases, even of different densities tend to mix
Yes, this is according to The Ideal Gas Laws. However, this only applies in a steady state.
My thoughts are that during the first day or two of fermentation, CO2 is effused from the surface of the beer at a rapid rate. Sufficiently fast enough to purge any gases from the headspace above the beer out of the airlock. Once this is done there is a high concentration of CO2 in the FV while the temperature is maintained.
Now, when the temperature is dropped for cold crashing, the gas cools and contracts. I drop my temperature from 20 degrees C to 4 degrees C. This would result in a 5.5% contraction in the volume of CO2 (Charles law) which, if there is a 10 litre headspace in the FV, that’s 550 mls of which about 150 mls is oxygen (1.5% of headspace). I enjoy a glass of wine with my dinner each evening so it takes 5 days to finish the bottle. The bottle is stoppered but has an air space over the wine, not CO2 or pure nitrogen. Never experienced oxidation from a 20% oxygen/nitrogen mix over 5 days so wouldn’t expect any from a 1.5% oxygen/CO2 mix over 3 days.
 

Seghes

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I’m trying first cold crash in my Fermzilla (in my newly acquired £15 fridge). Have set Inkbird to 2.5C and will see if the fridge even makes that. Being a newbie, I’m not sure if it’s ok to leave the Fermzilla with just the carbonation caps, (thus no bubble air lock) Seems to be no pressure inside, as I reckon fermenting has stopped. Should I put a bubble air lock back on? All this gas talk is a bit scary!
 

Banbeer

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If you're chilling down to those temps then fermentation will stop anyway but just be aware it could take a day or two to reach that temp athumb..
 

Buffers brewery

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I’m trying first cold crash in my Fermzilla (in my newly acquired £15 fridge). Have set Inkbird to 2.5C and will see if the fridge even makes that. Being a newbie, I’m not sure if it’s ok to leave the Fermzilla with just the carbonation caps, (thus no bubble air lock) Seems to be no pressure inside, as I reckon fermenting has stopped. Should I put a bubble air lock back on? All this gas talk is a bit scary!
Don’t have a Fermzilla but are they like a big PET blow moulding? If the wall thickness is small (like a coke bottle) it’s ok for pressure but not vacuum. Cooling will create a vacuum inside your sealed Ferm-z which, if the wall is thin, could cause a small collapse :confused.:
 

terrym

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Interesting thought. I've always assumed at the end of fermentation there is a nice cloud of CO2 covering the beer surface and the small amount of air drawn into the top of the FV has no chance of contact over a 3 day period.
As a physicist you will be well up on Brownian motion and its ability to homogenise fluids. The idea of a 'blanket of CO2' is something that may only exist for a short space of time.
 

Buffers brewery

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As a physicist you will be well up on Brownian motion and its ability to homogenise fluids. The idea of a 'blanket of CO2' is something that may only exist for a short space of time.
Quite right @terrym I am aware of Brownian motion and I have posted several thoughts on this subject on other threads. See #10 above for a fuller explanation of my opinion. Thanks for the prod :laugh8:
 

buddsy

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Hi Friends

I have a brew in my fermentation fridge. Its been fermenting for 1 week to yesterday Sat 19 Sep 2020.

OG 1064
SP 1012

Fermentation has slowed and I plan to bottle as per brewfather suggests next Sat. (14 days fermenting)

I want to cold crash as when I made my hop additions I didnt use the hop spider and chucked them straight in.

The bottom screen on my brewzilla done a pretty good job of capturing most of the hops but obviously I want to keep the sediment down to a min.

So my question is do I cold crash on Wed allowing 3 days to allow bottling on Sat? Or do I start Cold Crash on Sat after 14 fermentation.

Does it matter a jot?

Cheers all

buddsy
 

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I think it’s more a case of making sure fermentation has finished so a couple of SG readings a day or two apart that are the same will tell you that. Then cold crash. Depending on how big your brew is it could take a couple of days to chill right off. I usually leave my 5 gallon brews for a week before transfer.
 

buddsy

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Cheers sounds like a good plan.

I will take a few more readings. To be honest I had hoped it was all done a 1.015 but couple of days later it was 1.012.

Id preferred for it to be more around the 5% mark rather than the 7% its edging towards.

I guess I will give it time to finish and then time to chill.

This hobby seems to require patience for sure!

buddsy
 
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