Cold crash suck back from blowoff tube

[srcasko]

I wanted to share an observation about cold crashing and suckback through an airlock. During my last IPA ferment, I left the blowoff tube attached, assuming the additional CO2 volume left in the tube before the water level would be better than what a 3-piece airlock holds (nothing). Boy, was I wrong - the cold crash pulled in at least 300ml or starsan/yeast mixture. I channeled my best “RDWHAHB” and transferred it out of my Ss brewbucket and into a keg for carbonation, after tasting a gravity sample which seems fine. After filling the keg, I popped the top on the brewbucket to clean it and noticed that there seems to be a layer of starsan on top of the beer left in the fermenter - notice its milky white appearance apart from the gold color of the beer. Most likely this is due to the difference in specific weights of the different fluids, and I’m thrilled they didn’t appear to mix much.

Has anyone else observed this phenomena?

Cheers,
Scott

 

[day_trippr]

Welcome to HBT

Yes, the "Star San Suck Back" has inspired countless threads here.
Some folks have tried drawing off the clear-ish part to leave mostly beer behind.
Switch to S-locks before cold-crashes...

Cheers!

 

[srcasko]

Thanks for the comment, and hello from Holden!

 

[Queequeg]

I have had suckback of air which also completely oxidizes the beer . So there are risks with that too

 

[thehaze]

What if you just completely seal the fermenter and then cold crash it?

 

[Nagorg]

You will create a vacuum. If you use Better Bottles, they will collapse. A SS fermentor would fair better. Not sure about a glass carboy.

After my first (and hopefully last) StarSan suck-back event, I started using the S-Locks mentioned by Day_Tripper. I've had no noticeable problems from the air that will inevitably enter the fermentor. I've thought about applying low pressure CO2 (1-2 ps1) but I dont feel its worth the hassle or the potential cost of lost gas.

 

[thehaze]

You will create a vacuum. If you use Better Bottles, they will collapse. A SS fermentor would fair better. Not sure about a glass carboy.

After my first (and hopefully last) StarSan suck-back event, I started using the S-Locks mentioned by Day_Tripper. I've had no noticeable problems from the air that will inevitably enter the fermentor. I've thought about applying low pressure CO2 (1-2 ps1) but I dont feel its worth the hassle or the potential cost of lost gas.

So if I take my airlock away from my Speidel fermenters ( https://www.morebeer.com/products/speidel-plastic-fermenter-30l-79-gal.html ), screw on the cap it comes with, and cold crash for 3 days, it will create a vacuum so strong that it will damage my fermenter?

Or would this type of fermenter resist to the vacuum?

I am actually serious about it, as until now I just left my over-sized airlock on or used some tin foil, which I tied to the mouth of the fermenter, tightly. It still sucked some air, I could tell.

 

[srcasko]

I have had suckback of air which also completely oxidizes the beer . So there are risks with that too

I've also had issues with oxidation in hoppy beers and was wondering if it was also a cause or if it was from my packaging techniques. I was leaning towards packaging, because the beer seems to remain good in the keg, but not in a growler or can/bottle. However I'm pretty anal about making sure the bottles/cans are clean, santized, and purged with gas prior to filling, and capped right away.

I have a Pale Ale and an IPA currently at high krausen - I think i'll try rigging up the two-mason jar blowoff rig and see if i can handle the cold crash that way.

 

[day_trippr]

fwiw, I started cold-crashing under barely positive CO2 pressure (.5psi) a couple of years ago and believe it makes a difference wrt longevity...

Cheers!

 

[Nagorg]

fwiw, I started cold-crashing under barely positive CO2 pressure (.5psi) a couple of years ago and believe it makes a difference wrt longevity...

Nice... I guess I'd really only need the gas on long enough to get down to crash temp. Now I just need a regulator that will let me set that low of a pressure. Kinda hard on my TapRite..

 

[Nagorg]

So if I take my airlock away from my Speidel fermenters ( https://www.morebeer.com/products/speidel-plastic-fermenter-30l-79-gal.html ), screw on the cap it comes with, and cold crash for 3 days, it will create a vacuum so strong that it will damage my fermenter?

Or would this type of fermenter resist to the vacuum?

Cant really speak to that. I think those are a thicker plastic so they'd hold up better than the thinner Better Bottle types. But you'll still create a vacuum as the temp drops.

 

[brewbama]

Or make/buy one of these...

 

[Nagorg]

Or make/buy one of these...

Those do solve the suck-back problem but dont really address the air that enters the fermentor during cooling..

 

[brewbama]

True.

 

[Nagorg]

That is if you care about that anyway...

 

[gromitdj]

I took @day_trippr 's advice in these forums and ordered this low pressure regulator and a couple of appropriately sized barbs. Hooked it up to my CO2, and it has worked a treat..

Also, if you can successfully seal a fermenter for cold crash, as soon as you remove that seal, air is going to rush in.

ETA: of course there are some that believe there is enough air in Beverage grade CO2 to oxidize the beer anyhow, so maybe it's all for nothing anyhow...

 

[whovous]

Those do solve the suck-back problem but dont really address the air that enters the fermentor during cooling..

I don't get it. Where does the air come from? I thought the two jar set-up insured you'd have mostly CO2 in the jars come suck-back time.

 

[day_trippr]

The problem with the jar solution is volumetric: the jar headspace is dwarfed by the headspace of a typical fermentor.
So, yes, whatever CO2 was captured by the jars will get pulled in, followed by room air.
And once the path to room air is opened there's nothing to keep O2 from establishing/maintaining its destined partial pressure inside the fermentor...

Cheers!

[edit] ps: Please note that the regulator linked by @gromitdj is fairly specific to this application. While it resembles a barbecue grill regulator, it is designed for relatively low pressure input, thus wrt liquified gas it's definitely a secondary regulator that must be down-stream of a primary regulator.
Conversely, a typical barbecue grill regulator will not work in this application as its internals are designed around very high cylinder pressure as a primary regulator. Putting one of those down stream of a primary CO2 regulator will result in zero output.

 

[foles]

Best solution - don't cold crash. I'd rather crash in serving keg and have some yeast settle there than introduce O2 to my beer.

I gradually reduce temps only by 3-4C over a few days, to encourage some flocculation before kegging.

 

[NTexBrewer]

The problem with the jar solution is volumetric: the jar headspace is dwarfed by the headspace of a typical fermentor.
So, yes, whatever CO2 was captured by the jars will get pulled in, followed by room air.
And once the path to room air is opened there's nothing to keep O2 from establishing/maintaining its destined partial pressure inside the fermentor...

Cheers!
.

I disagree. The second chamber of the CO2 catcher has starsan in the bottom. The “blowoff tube” is submerged in the starsan. When you cold crash if you did things right you may suck some starsan into the first chamber but as long as the “blowoff tube” stays submegred in starsan you are not introducing outside air.

Here is my system, the Tupperware container has about 4” of starsan in the bottom. The mason jar captures the CO2. During fermentation excess CO2 goes through the white tube and bubbles through the starsan. The hole on the Tupperware lid is big enough for the escaping CO2 to not pressurize the Tupperware container.

When I cold crash, some starsan may get sucked into the mason jar but it has never sucked up all of the starsan.

I use this system on my hoppy beers. For other beers I typically just soak some cotton balls in starsan, remove the airlock and pack the bung with the cotton balls.

 

[gromitdj]

<snip> Please note that the regulator linked by @gromitdj is fairly specific to this application. While it resembles a barbecue grill regulator, it is designed for relatively low pressure input, thus wrt liquified gas it's definitely a secondary regulator that must be down-stream of a primary regulator.

Thanks, Day_Trippr, I should have stated that I have it connected downstream of my CO2 regulator and provide the low pressure regulator with approx. 2 psi. I believe the low pressure regulator provides .5 psi. Which wasn't even enough pressure to pop the rubber stopper out of the lid of my fermonster. And thanks for the suggestion!

 

[mscroggi]

Here is a thought.. What about the idea of stretching a balloon over the fermenter exhaust like what the ancient technique used by home wine makers? Or even using a balloon in place of the gas resovoir. Surely over a weeks fermentation time, it would generate more gas than it would suck back in after cold crashing. This would give a flexible volume of gas collected and it would remain sealed.

 

[mscroggi]

Here is a thought.. What about the idea of stretching a balloon over the fermenter exhaust like what the ancient technique used by home wine makers? Or even using a balloon in place of the gas resovoir. Surely over a weeks fermentation time, it would generate more gas than it would suck back in after cold crashing. This would give a flexible volume of gas collected and it would remain sealed.

I just ran across this - https://www.brewhardware.com/product_p/ccguardianv2.htm which handles the issue much more elegantly.. It seems worth the $12

 

[mscroggi]

Here is a thought.. What about the idea of stretching a balloon over the fermenter exhaust like what the ancient technique used by home wine makers? Or even using a balloon in place of the gas resovoir. Surely over a weeks fermentation time, it would generate more gas than it would suck back in after cold crashing. This would give a flexible volume of gas collected and it would remain sealed.

Ah I see people are doing this. This makes total sense to me..

 

[rudylyon57]

Here is a thought.. What about the idea of stretching a balloon over the fermenter exhaust like what the ancient technique used by home wine makers? Or even using a balloon in place of the gas resovoir. Surely over a weeks fermentation time, it would generate more gas than it would suck back in after cold crashing. This would give a flexible volume of gas collected and it would remain sealed.

Another version of the CO2 bladder idea-compliments of the Brulosophy team. Just after active fermentation is winding down, tee balloon into blow-off tube, squeeze balloon of air, submerge the blow-off tube in a few inches of liquid and its surprising how full and tight the mylar balloon will become with just a few inches of pressure head. Cold crash to 32-35F makes the balloon shrink by 50% in volume or so allowing fermenter to draw excess CO2 from balloon. Not sure if it really helps beer quality but its so simple I plan to use it whenever a cold crash is needed.

 

[mscroggi]

Ah yes.. I have everything to build this except the hose tee.. I agree its so simple and cheap.. why not do it.. Mylar balloon at Walmart 97 cents and whatever the cost of the hose tee. Everyone has extra tubing laying around.. Awesome..

Searching the internet for different solutions.. Some of way over-thought in my opionion. But I get that it's fun to engineer a solution.

 

[Bobby_M]

Ah yes.. I have everything to build this except the hose tee.. I agree its so simple and cheap.. why not do it.. Mylar balloon at Walmart 97 cents and whatever the cost of the hose tee. Everyone has extra tubing laying around.. Awesome..

Searching the internet for different solutions.. Some of way over-thought in my opionion. But I get that it's fun to engineer a solution.

You ever smell what the inside of a mylar balloon smells like?

 

[PeteSeattle]

Or make/buy one of these...

View attachment 560919

Perfect. Problem solved.

 

[brew703]

You ever smell what the inside of a mylar balloon smells like?

The ones I have don't smell. And I've used the mylar balloon three times and didn't notice any imparted flavor or aroma by using the mylar vs the bladder you sell.
I looked at yours but every time I went to your site the bladder was sold out.

 

[azdavid]

I use the Cold Crash Guardian from BobbyM at Brewhardware.com
For a simple device it does exactly what it is designed to do. Put it on at the start of fermentation and it is good to go when you are ready to cold crash.
Here is a video of it in action
and a link to the website https://www.brewhardware.com/product_p/ccguardianv2.htm

 

[mscroggi]

I use the Cold Crash Guardian from BobbyM at Brewhardware.com
For a simple device it does exactly what it is designed to do. Put it on at the start of fermentation and it is good to go when you are ready to cold crash.

Yeah I am really interested in that device.. my problem with it is the horizontal volume requirements.. I don't think it will fit in my freezer straight to the side like that.. maybe its smaller than it appears.

 

[azdavid]

Yeah I am really interested in that device.. my problem with it is the horizontal volume requirements.. I don't think it will fit in my freezer straight to the side like that.. maybe its smaller than it appears.

I have a 30 L Speidel and it does extend about 4 inches beyond the diameter but I just align it so it is towards the corner of my chamber, Since I try to keep the fermenter away from the walls of the freezer anyway it fits perfectly right in the corner.

 

[mscroggi]

I have a 30 L Speidel and it does extend about 4 inches beyond the diameter but I just align it so it is towards the corner of my chamber, Since I try to keep the fermenter away from the walls of the freezer anyway it fits perfectly right in the corner.

That could work.. I think I might give it a go.. I do wish the bag was separated with a bit of tubing for more flexibility.. I only have a few inches above the fermenter.

In the meantime I did make good with my own implementation -

So far so good. My brew has only been in the fermenter since Sunday. It filled that mylar balloon in about 3 hours.

 

[rudylyon57]

You ever smell what the inside of a mylar balloon smells like?

Only the ones filled with helium and its inert . Seriously though I have not. Respectfully though, are you implying they have an odor that might carry-over into beer?

 

[mscroggi]

Yeah I am really interested in that device.. my problem with it is the horizontal volume requirements.. I don't think it will fit in my freezer straight to the side like that.. maybe its smaller than it appears.

My Cold Crash Guardian arrived. It is smaller than I thought.. so I dont think space is going to be the issue.. also the bag does attach with a fitting that allows a piece of tab to separate the bag from the top of the fermenter. It is more elegant than the mylar balloon. The price is good too.. except for the shipping. I paid as much to ship it as the unit cost.

 

[mscroggi]

Or make/buy one of these...

View attachment 560919

One thing about having one of these.. It looks like the parts could also be used as a randall..

 

[Radboud]

I use a SS fermenter. I got a few 1/4" NC gas-in posts from Ali E. that neatly fit in the predrilled hole for the airlock bung. What I do is during active fermentation attach a disconnect with a hose in some Star San, when I cold crash I remove the disconnect+hose and slightly pressurize (or un-vacuum) the whole thing with CO2 a few times during the temp drop.

 

[USMChueston0311]

Just cold crash in a keg hooked up to co2.... or invest in a conical and add a head pressure of co2. Simple. Brewed dozens of batches in carboys and out in fridge w airlock with no issue, EVER

 

[Nagorg]

To be honest, I'm sure that there may be some potential risk from O2 entering during the cold crash. It does make sense but its unclear to me how much this actually influences the finished product. I cold crash often and like @USMChueston0311 , I don't believe any of my beers have had problems from it.

The idea of near zero O2 exposure during a cold crash sounds good but I maintain my initial response; I don't feel its worth the hassle. I think I'll stick to the K.I.S.S. principle for the time being..

Back to the OP, those jar solutions seem great for eliminating suck-back. They probably do a lot to minimize the related O2 infiltration too since they would be full of CO2 post fermentation and it would take a lot of suck-back to pull O2 in from the jars, up the tubes, into the fermentor and into your beer.

If I needed a blow-off tube and didn't want to remove it for a cold crash, I'd set myself up with the jars...

 

[MaxStout]

In another thread, someone did the math and determined that even with 1.5 gal. headspace and including the space in the jars, the suckback from chilling from 60s to just above freezing would only involve less than 1 qt. of contraction. If you get one of those "CO2 Harvester" units, use 1/2 gal jars and about a quart of Starsan in them. There won't be any air getting back into your fermenter.