Preventing O2 ingress when cold-crashing for lagering - ideas?

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MaxStout

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I have a dilemma. I have 5.75 gallons of lager (pitched W-34/70) in a 7 gal. Brew Bucket the ferm chamber, and in a couple weeks I'll be cold-crashing to lager for another month or so. I normally use a CO2 Harvester with 1/2 gallon canning jars to collect enough CO2 for the inevitable suck back. However, on day 2 of fermentation I discovered that CO2 Harvester leaks like a sieve--no airlock activity. I disconnected it and replaced with an s-bubble airlock with vodka.

Now that fermentation has slowed I'll need to think about dropping the temp for lagering in a few weeks, without any external reservoir of CO2 to draw from. I have not opened the Brew Bucket lid, nor have I dropped temp yet, so there should be fairly pure CO2 in there now. I have read through several threads, but not much info applying to my situation.

Difficulty: I bottle, not keg.

I see some possible solutions, but wanted to get some input from others.

1. The mylar balloon idea looks promising, as I have a tank of CO2.

2. Someone in one of those threads suggested simply plugging up with a bung. I don't recall what type of fermenter they were talking about. Not sure if that's a good idea for my Brew Bucket, as it has the regular style lid, not the pressure type. Even so, I don't know how much negative pressure it can withstand. Maybe someone knows if I could do this?

3. Get a spunding valve. That would vent off any excess pressure if there is any further yeast activity (unlikely), but in a negative pressure situation, I'm back to the problem in #2.

This is new to me, as I usually have the CO2 in those jars to draw from. Any ideas would be appreciated!
 
1. The mylar balloon idea looks promising, as I have a tank of CO2.
That! ^

Since you don't know if your bucket lid will remain 100% sealed* when there's any overpressure, the CO2 filled mylar balloon is the most straightforward solution, effectively being a CO2 filled contraction reservoir.

* As long as you're sure the CO2 harvester itself was leaking, and not your fermenter lid or gasket.
 
That! ^

Since you don't know if your bucket lid will remain 100% sealed* when there's any overpressure, the CO2 filled mylar balloon is the most straightforward solution, effectively being a CO2 filled contraction reservoir.

* As long as you're sure the CO2 harvester itself was leaking, and not your fermenter lid or gasket.

I tested the CO2 Harvester in a bucket of water and blew into the inlet hose. Bubbles came out like crazy from under the jar lid. I replaced the jar lid and put a new silicone gasket on the device. Still leaked. I tried using keg lube on the lid and mouth of the jar. Still leaked. I gave up on it.

The Brew Bucket, OTOH, is airtight as can be. I'm not worried about that leaking, just if it can handle some negative pressure. It's stainless steel, but thin.
 
I've been looking a bit a stainless brew buckets. I think you are probably talking about SS Brewtech since you capitalized it but might be important to note which model even. I don't know if the first version is the same as the second?

Water bladders also work in place of mylar ballons. Mylar balloon may be simpler to get sealed if this is just a one off use. The cap threads on the bladders can be different and if you aren't getting a bladder with a hydration hose attached, it might be a PITA to get the fittings you want. I know brewhardware.com has a bladder collection system for sale if you decide the mason jars aren't working for you.
 
I’ve used SS brew buckets for a few years and I have over-pressued them once or twice on transfers. The gaskets on the lids will burp the excess pressure. I’m sure the same will happen in reverse if you choose to simply bung the fermenter for the crash. In other words, I don’t think you have to worry about oil canning the fermenter—but I only think that, I don’t actually know that.

Ultimately, bunging it will just postpone the issue: eventually the atmosphere has to equalize and it will do it instantly. I suppose you could lager it under vacuum, then let it warm up to a few degrees above the point at which you crashed… meh, I don’t like that.

Here’s an idea I’ve toyed with, but never implemented. If you buy large quantities of hose at a time, I typically buy 10’ at a time every few years, a very, very long blow off (several feet) might give you enough volume to get away with it on a lager if you skip the D-rest and allow it to finish in the mid-50s. Sure it’ll cost you some time, but it’s better than oxygen ingress.

Personally, I think the mylar balloon is the superior idea. Also, while it’s best practice to lager around freezing, you don’t have to crash that low to still get the benefits—it just takes a bit longer. A softer crash will ease the load on your emergency anti-suck back rig.

Some daft ideas, but perhaps useful.
 
I tested the CO2 Harvester in a bucket of water and blew into the inlet hose. Bubbles came out like crazy from under the jar lid. I replaced the jar lid and put a new silicone gasket on the device. Still leaked. I tried using keg lube on the lid and mouth of the jar. Still leaked. I gave up on it.

Mine's finicky as well. I basically did some of what you did but it worked for me. Once it was sealed well I simply don't unscrew it any more. If any water / star san solution gets into it I dump it out of course after kegging but leave the lid on when doing so and count on it air drying afterwards. So far, so good. If the system otherwise worked for you, maybe try again? And / or verify the gasket isn't torn.

The harvester is a great idea but the execution for the lid sealing at least could indeed be improved.

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Mine's finicky as well. I basically did some of what you did but it worked for me. Once it was sealed well I simply don't unscrew it any more. If any water / star san solution gets into it I dump it out of course after kegging but leave the lid on when doing so and count on it air drying afterwards. So far, so good. If the system otherwise worked for you, maybe try again? And / or verify the gasket isn't torn.

The harvester is a great idea but the execution for the lid sealing at least could indeed be improved.

View attachment 839758

I have extra gaskets, as they are short-lived. And I did replace it (along with the Mason jar band), but finding there was still a leak.

I think the problem is that the lid insert is thick, about 1/16". Being thicker than a standard Mason jar center lid, the threaded band only tightens about 1/4 turn or so onto the jar. And those silicone gaskets deform too easily--they ooze out the rim, even if the band isn't tightened very much.
 
Not really relevant for your current dilemma, but for next time. Struggling with the same issue, I decided to fit keg post bulkheads to my plastic FVs then use a low-pressure propane regulator (<3 psi) to stop a vacuum forming during cold crash. Works like a charm.

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A trip to the dollar store and I got a few mylar balloons. I rigged some tubing and a way to fill it from a CO2 tank using a carbonation cap. The balloons have a one-way valve I had to cut off, then just some electrical tape to seal it on the tubing.

Doing an airtightness test. It's holding up so far.

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A trip to the dollar store and I got a few mylar balloons. I rigged some tubing and a way to fill it from a CO2 tank using a carbonation cap. The balloons have a one-way valve I had to cut off, then just some electrical tape to seal it on the tubing.

Doing an airtightness test. It's holding up so far.

View attachment 839793
I really like that bottle support! Great simple idea. 👍🏻
 
A trip to the dollar store and I got a few mylar balloons. I rigged some tubing and a way to fill it from a CO2 tank using a carbonation cap. The balloons have a one-way valve I had to cut off, then just some electrical tape to seal it on the tubing.

Doing an airtightness test. It's holding up so far.

View attachment 839793
I'm worried for your valentine, it'll be a very heavy heart!!
 
for cold crashing in my brewbucket, I use a cask breather (normally used for cask ales). connect a co2 source to the IN side and it allows enough co2 in to maintain even (atmospheric) pressure in the fermenter.
 

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I use a cheap BBQ propane regulator down stream from a standard primary CO2 regulator to supply 11" WC (~0.4psi) of CO2 pressure to my fermentors during cold-crashing. As all my gas systems use EVABarrier tubing with PTC fittings it takes 5 seconds to insert the low pressure "secondary" regulator when needed...

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Cheers!
 
It's that gadget again!
Sometimes it feels like I carry it around with me, it gets so much use. Good for sampling pressure too, especially from non pressure rated FVs, difficult to reach in a keezer. I’m surprised there’s nothing like it commercially available to home brewers. Probably will be soon now.
 
If you have a food saver/vacuum sealer and an extra bottling bucket valve, put one of these together. I just inflate it, squeeze the air out a couple of times then put it on and cold crash.

I have a Foodsaver and lots of bucket valves. How do you seal the bag onto the valve inlet? I can't tell from the pic. I just used electrical tape for the balloon thingy I cobbled together.
 
I usually closed transfer to a keg first, pressurize to 20 psi and start lowering the temp 2 degrees F per day until I hit 32 F. If pressure drops below 5 psi due to carbon dioxide solvation, I bring it back up to 20 psi. I typically lager for a month before pulling the keg and then bottle from the keg if I need to do so.
 
Wouldn't kegging from a bucket involve at least the same amount of suck-back as cold crashing? Probably a lot more even...
 
Wouldn't kegging from a bucket involve at least the same amount of suck-back as cold crashing? Probably a lot more even...

Depends on your technique. As long as you have a post on your bucket lid, you can connect the purged keg gas post to the bucket to equalize pressure, then connect the spigot to the keg liquid out. Raise the bucket above the keg and open the spigot. I usually start by replacing any air lock with a bolt under positive pressure so I can keep the whole assembly above atmospheric. I actually use a conical fermenter (Fast Ferment), but the process is the same. Here is a picture of my setup - excuse the airlock (plugging the hole is an improvement in the process).

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I have a Foodsaver and lots of bucket valves. How do you seal the bag onto the valve inlet? I can't tell from the pic. I just used electrical tape for the balloon thingy I cobbled together.
Just cut a round hole big enough for the shank to fit through, snug down the nut, then seal the bag closed.
 
Depends on your technique. As long as you have a post on your bucket lid, you can connect the purged keg gas post to the bucket to equalize pressure, then connect the spigot to the keg liquid out. Raise the bucket above the keg and open the spigot. I usually start by replacing any air lock with a bolt under positive pressure so I can keep the whole assembly above atmospheric. I actually use a conical fermenter (Fast Ferment), but the process is the same. Here is a picture of my setup - excuse the airlock (plugging the hole is an improvement in the process).
I use this same process for the brew buckets. Works great and is closed.
 
Depends on your technique. As long as you have a post on your bucket lid, you can connect the purged keg gas post to the bucket to equalize pressure, then connect the spigot to the keg liquid out. Raise the bucket above the keg and open the spigot. I usually start by replacing any air lock with a bolt under positive pressure so I can keep the whole assembly above atmospheric. I actually use a conical fermenter (Fast Ferment), but the process is the same. Here is a picture of my setup - excuse the airlock (plugging the hole is an improvement in the process).

View attachment 839845
I agree this would do the trick. But if your able to pressurise the bucket (even if the pressure would be very low) you wouldn't need to transfer to a new bucket/keg in my opinion. Then you can just cold crash in the original and still avoid stuck-back. Or am I missing something?
 
Just cut a round hole big enough for the shank to fit through, snug down the nut, then seal the bag closed.

That could work with the mylar balloon as well. Never considered a plastic valve, using the nut to seal the bag or balloon opening. Fill with CO2, shut the valve, connect to FV, open valve.

I like how this thread's turning into "show us your CO2 collection devices." HBT crowdsourcing.
 
I just cobbled together one like @JohnDBrewer's. Tightening the valve nut on the balloon's opening didn't provide a good seal for me, too many wrinkles. Maybe a vac seal bag works better.

Anyway, I just sealed it with elec tape. Filled up the balloon, closed the valve, will wait and see if it holds CO2. The other one I made yesterday hasn't lost any.

I still have one balloon left. I could fill it and give it to my wife, but a CO2-filled balloon that sinks to the floor probably sends the wrong message.

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If you have a food saver/vacuum sealer and an extra bottling bucket valve, put one of these together. I just inflate it, squeeze the air out a couple of times then put it on and cold crash.
I use a similar device to this, from Bobby and Brewhardware:

https://www.brewhardware.com/product_p/ccguardianv3.htm
Their cold crash guardian is great if you don't have time to DIY. This is set up to work with a gas post.
 
Well, the second DIY device I made yesterday (with the bucket valve) didn't hold CO2. Did a leak test and the spot where I taped it up onto the valve inlet was leaky. The first device I made is still holding gas. My taping job was better on that first one and the tubing I attached the balloon to is smoother than the valve, so better seal.

Nevertheless, I decided to get a Cold Crash Guardian from Brew Hardware (I needed a few other things, anyway). It should arrive in time for the cold crash. I'll just squirt in some CO2 from a tank, connect, then cold crash.
 
I've been wondering about the "suck back" issue lately, as I'll be attempting to cold crash my first brew this winter out in the garage. Would using a "colmatore" (like the winemakers) be useful? Seems like a larger 3 piece airlock with the option of "topping up" as the wine contracts. Any thoughts?
 

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Seems like a larger 3 piece airlock with the option of "topping up" as the wine contracts.

A goal with beer is to not have "air" go back into the fermenter - it contains oxygen which will start aging the beer and you'll be losing hops flavor. Hence the devices that fill with CO2, and then return that CO2 to the fermenter.
 
I'm not too familiar with colmatori, but I know with standard 3-piece airlocks, oxygen will pass back through the water in the airlock when you cold crash. These looks like they fuction similarly, but I couldn't say for sure that it can allow air back in with a pressure drop.

Someone correct me if I'm wrong, but a device that can trap CO2 is probably the safest bet to avoid oxygen.
 
A goal with beer is to not have "air" go back into the fermenter - it contains oxygen which will start aging the beer and you'll be losing hops flavor. Hence the devices that fill with CO2, and then return that CO2 to the fermenter.
That's the stated purpose of this device as well. The airlock has a reservoir (an extension of the barrel contents), and what looks like a larger airlock portion that is more "user friendly" with regards to removing the center piece. It seems as though the water portion has enough to seal the air out, but not enough to suck into the chamber (ie: the water seal will break).....being larger than a normal airlock, it would allow the winemaker/brewer time to break the seal himself, and top up with something perhaps carbonated (like a beer maybe?). There's not much online about the techniques they use, but somehow they're able to avoid suck back without oxidizing their wines.
 

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That's the stated purpose of this device as well. The airlock has a reservoir (an extension of the barrel contents), and what looks like a larger airlock portion that is more "user friendly" with regards to removing the center piece. It seems as though the water portion has enough to seal the air out, but not enough to suck into the chamber (ie: the water seal will break).....being larger than a normal airlock, it would allow the winemaker/brewer time to break the seal himself, and top up with something perhaps carbonated (like a beer maybe?). There's not much online about the techniques they use, but somehow they're able to avoid suck back without oxidizing their wines.

Do vintners typically cold crash their wines? If not, that's the reason they don't get oxidation
 
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Do vintners typically cold crash their wines? If not, that's the reason they don't get oxidation

Seems that they are concerned about some suck-back due to evaporation through the barrels. For the ones that use wood of course. So there may be some commonality there.

I didn't quite get what the device does, something about filling it with wine? I'm only familiar with the typical homebrew 3-piece airlocks, or the single piece with the sideways S shape in them. I looked somewhat carefully at it but the glass makes it hard to know what's going on. A little Google searching just got frustrating.
 
Do vintners typically cold crash their wines? If not, that's the reason they don't get oxidation
Winemakers are subject to the same challenges of oxidation as brewers.
They use airlocks the same way we do....except (as I've now discovered) that they also use them to mitigate the potential for oxidation VIA suck back.

Info is scarce, but it seems that the colmatore style airlock is basically like a regular 3 piece (in functionality), except it has a reservoir below the "airlock" section, it's larger (around the size of a 2 liter pop bottle), reservoir can be filled VIA the large tube in the airlock portion, and the center piece (lock) can be readily removed for filling.
 
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