Closed-system pressurized fermentation technique!

crane said:

You are on the same track that I use for dry hopping, however I have been successful with just using the smaller coarser screen that fits directly on the dip tube without cutting the dip tube. I have used up to 3oz of pellet hops per 5 Gallon corny keg but have not had any clogging issues.

I will let it ferment out completely for 7 days as I don't have time during the week with work to transfer sooner. I add the hops to my dry hopping keg and purge it with CO2, then transfer the beer in. No need to try and time it so there is still fermentation activity after you transfer.

Click to expand...

Interesting.

I have it on good authority that at least one of the prominent purveyors of NE IPA dry hops under pressure, so I'm thinking if I pull at four to five days into primary into a pressurized dry hop keg, that I should have good results.

Epic thread - thanks to Wortmonger, SankePankey and everyone for all the helpful tips.

I'm on my third batch using this technique and loving it. I didn't even clean out the keg after transferring the last batch - just threw the next brew right onto the yeast cake.

I've been starting the ferment with a blowoff for the first couple of days, as I'm wanting my wild yeast to produce some esters. I then attach the valve, and let pressure creep up over the next 4 to 5 days to about 25psi (at about 65F), at which point the ferment is pretty much done.

While it does require daily checking/adjustment to ensure pressure doesn't drop/rise out of range, I love the fact that that there's no oxygen exposure, and the beer is already carbed up.

As a bonus, I can manhandle the fermenter to rouse the yeast, or move to my cool room without worrying about spilling, air exposure, or breaking the vessel.

Go Sanke!!

Does anybody NOT pressure transfer to clean serving kegs when their fermenting is finished? I have religiously transferred all the time, but am now considering not to. I have 10 gallons coming out soon. What kind of problems taste wise will there be if I don't get the beer off the yeast? How long do I have to drink it up? Thanks...
MS

Also interested in the answer to the question above. I have to dry hop my current brew, so it makes sense to rack on top of the hops, but I would love to do single keg the whole way through if it isn't detrimental.

And my first ever pressure fermentation is now on day 2, so I guess it's about time I subscribe to this thread since its been so helpful.

I'm running a 2 corny setup, one for fermentation one for blowoff/CO2 capture. I have a full 5 gallons in the ferm keg and no blowoff at all with a little defoamer. I'm pretty surprised because there wasn't much headspace. Pitched WLP090 yesterday and I'm already 30% done!

I asked the same question here before, but not too much answere came.
Yes, I tried the method leaving the beer in the fermenting corny kegs (and serving from it) more then one year ago, and I did not recognize too much problem with it, so I use this methodt since. Now I have nine cornies, and only one is held with original dip tube for tap cleaning purposes, the others are all fermenting/serving cornies with shorter/bended dip tube. The keg sanitizing process therefore is not necessery. I do not use starsan since more than a year. When I clean the corny, I use only oxyclean. I use lazy chill: hot wort goes to corny, I close it, and the corny goes to a barrel filled halfway with water. I use stir plate with real wort starter, so I pitch (without oxigenation) next day in my fermentation chamber (freezer+stc1000). I start fermentation in open way with blowoff tube through gas port with removed poppet/tube. After some days when the bubbles are slow enough, I reassemble the poppet into gas port and put my spunding valve on. After diacetyl rest and cold brake I remove spunding valve and cornies goes to keezer on tap. I pur the first half pint out.
- yeast harvesting is not so easy
- the first pints can be a bit hazy, but it disappears. Tha last half pint can also be hazy.

Thanks macok, that makes sense. I don't want to cut any dip tubes, but I don't mind a couple of cloudy pints if it saves a transfer. The first few pints could just be my yeast for the next batch. I also "lazy chill" so I'm guessing the longer dip tube will help with pulling the yeast out of the keg. How long have you gone with one sitting on the yeast?

-You can cut it. Later you can restore the original state pulling a proper small silicone tube onto the steel tubes to join again the tubes.
- you can bend the dip tube carefully
- you can assamble a small stainless steel cup onto the original dip tube
Anyhow, i dont suggest using the original dip tube. It is better if it is above the yeast cake.

It was about 3-4 months maximum. I simpy drinked it before having more experience. If you buy some belgian beer it has little yeast in the bottle bottom. And it is not always cooled 4C cold....

Last night we floated the keg of my first pressure fermentation. Yeast pitched on 12/12, transferred to serving keg on 12/22, floated keg with help from family & friends on 12/24. So nice already having it carbed up and doing the transfer was a breeze.

It was a good beer to drink fresh, but there was a huge difference from when it was first transferred and 2 days later. Soooo good after it smoothed out for another 48 hours. I don't plan on adhering to that tight of a timeline regularly, but it was awesome to know that I can in a holiday pinch.

Here is what fermentation looked like. I sampled a lot more than I usually do just to get an idea of what the pressure fermentation schedule looks like.

Oh, and a tip for adding the gelatin under pressure if interested - I put the gelatin in a soda bottle, put a carbacap on the soda bottle and pressurized it too about 50psi, then used a jumper from the soda bottle to the keg gas post. I had to squeeze the last little bit out, but it really worked like a charm.

When pressure transferring to serving keg(s), how are you prepping the corny keg to remove oxygen? On the Low Dissolved Oxygen (LODO) Brew Science thread it was mentioned to cut the gas tube to max shortness, over fill with starsan and push it out with co2.
MS

1MadScientist said:

When pressure transferring to serving keg(s), how are you prepping the corny keg to remove oxygen? On the Low Dissolved Oxygen (LODO) Brew Science thread it was mentioned to cut the gas tube to max shortness, over fill with starsan and push it out with co2.
MS

Click to expand...

I use the CO2 created during fermentation to purge the serving keg, details are in my post https://www.homebrewtalk.com/showpost.php?p=7457715&postcount=2230

1MadScientist said:

When pressure transferring to serving keg(s), how are you prepping the corny keg to remove oxygen? On the Low Dissolved Oxygen (LODO) Brew Science thread it was mentioned to cut the gas tube to max shortness, over fill with starsan and push it out with co2.
MS

Click to expand...

I've recently had a discussion with @schematix on this very subject. Hopefully he sees this and can give you his take. He does cut the gas tube short to be able to maximally fill and purge the corny.

I proposed the idea of having a fermenting corny -> filter housing (optional to catch blowoff) -> starsan filled serving corny -> empty corny -> spunding. The idea being that your fermentation naturally pushes the starsan out of the serving keg and into the NEXT batches serving keg. The obvious draw backs here that you need another extra keg, extra connections, extra points of failure... schematix pointed out that store bought co2 is cheap enough to not need to harvest the natural stuff for just the purge.

I have cut all my gas tubes down. This enable me to close the lid and connect the liquid post to the fresh water tap to fill the keg with water. I vent off the air with another hose and then give the keg a wobble to get the last air out. I then have a keg completely full of water.

I next use my collected co2 to push out the water out of three kegs (I do a 48l batch) and am left with clean kegs at about 8psi.

I then put them on a scale, put about 10psi on the fermenting keg and counter pressure fill until I get the correct weight in each keg (at about 2 litres a minute). The third Jed is a short on and only gets about 12l.

T

Tegra said:

I have cut all my gas tubes down. This enable me to close the lid and connect the liquid post to the fresh water tap to fill the keg with water. I vent off the air with another hose and then give the keg a wobble to get the last air out. I then have a keg completely full of water.

I next use my collected co2 to push out the water out of three kegs (I do a 48l batch) and am left with clean kegs at about 8psi.

I then put them on a scale, put about 10psi on the fermenting keg and counter pressure fill until I get the correct weight in each keg (at about 2 litres a minute). The third Jed is a short on and only gets about 12l.

T

Click to expand...

Can you elaborate on your co2 collection procedure? Also, just tap water and no sanitizer in those kegs before use?

thekraken said:

I've recently had a discussion with @schematix on this very subject. Hopefully he sees this and can give you his take. He does cut the gas tube short to be able to maximally fill and purge the corny.

Click to expand...

I posted my write-up with pictures in another thread....

1MadScientist said:

When pressure transferring to serving keg(s), how are you prepping the corny keg to remove oxygen? On the Low Dissolved Oxygen (LODO) Brew Science thread it was mentioned to cut the gas tube to max shortness, over fill with starsan and push it out with co2.
MS

Click to expand...

I'll share another method I saw someone post recently. I don't like it because it sounds like a pain in the butt to do all the time, but I think it would be 100% as effective as shortening the dip tube.

When doing the water purge procedure, remove the gas post and original length gas dip tube. Fill the keg via the liquid dip tube as usual. Do the usual 45 degree tilt/shake/tilt to get all the bubbles out from under the lid, then re-insert the gas dip tube (water still trickling), and loosely screw on the post. Then disconnect the supply water and firmly tighten the gas post.

For those of you using cornies: what size ID tubing are you using on your lines to your blowoff vessel? I'm guessing the bigger the better but maybe it doesn't matter?

thekraken said:

For those of you using cornies: what size ID tubing are you using on your lines to your blowoff vessel? I'm guessing the bigger the better but maybe it doesn't matter?

Click to expand...

I just hook the gas out of my fermentor Cornie to the liquid in of an empty (pressurized to about 5 psi) which has my spunding valve attached to it.

The empty keg catches any blowoff if I fill the fermentor too high.

schematix said:

I'll share another method I saw someone post recently. I don't like it because it sounds like a pain in the butt to do all the time, but I think it would be 100% as effective as shortening the dip tube.

When doing the water purge procedure, remove the gas post and original length gas dip tube. Fill the keg via the liquid dip tube as usual. Do the usual 45 degree tilt/shake/tilt to get all the bubbles out from under the lid, then re-insert the gas dip tube (water still trickling), and loosely screw on the post. Then disconnect the supply water and firmly tighten the gas post.

Click to expand...

This is what I ended up doing. Thanks for the idea.

So awesome this thread is still kicking!

Hello to everyone and thanks for the great posts. i am new to the forum and this thread. I’m definitely interested in this type of fermenting as i have some tight space requirements and would like to either dual purpose my keezer as fermenting chamber, or be able to use higher ferm temps under pressure and use another space i have available with less temp control. I tried to access the wiki linked on the first page but i get a blank screen from both iPhone and a iMac. If its ok, can i get some clarification on a few points in the process?

###############Keg Filling#################
How high is best practice?
I have read some posts where low volume was used(4.5 gl) and a blowoff until after high krausen, and others that say fill up to the weld and pressure will keep the Krausen limited to 1cm.

###############Pressure###############
I read minimum 5psi to start/ maintain seal to no more than 25 psi, but is there an accepted schedule of ramping pressure from low to high during fermentation to reach carbonation at finish time?
Also, how does this relate to ferm temperature? Is process something like this(with typical fermentation)?:

Days
1———>2———>3———> 4———>5———>6———>7———>8———> 9———>10

5psi —> naturally build to 15psi —> hold w/ spunding—> ramp to 25 ——> chill and serve

65F ———————> Ramp schedule to ~70-72 ———————>Diacetyl rest ——>Finish


###############Temperature###############
I read Brulosopher’s blog post comparing ~60F temp to a ~80F temp under pressure with no perceptible difference, but not sure if that is OK in working practice.
1. How high of temps do you/can you run with a typical ale yeast? or Lager?
2. Any experience with the White Labs WLP925 High temp Lager yeast? There are many recipes i would like to try with this yeast so I would love to hear your impressions of it.

###############Dry Hopping/Flavoring###############
How to access the pressurized keg to add flavor?
1. Dry Hops/Flavor added immediately to wort. ingredients stay in keg entire time?
2. Depressurize, add flavoring, re-pressurize with CO2? doesn’t this defeat the purpose of staying oxygen free?
3. some other method?

###############Sampling###############
I had one infection in one of my first brews and it was a real bummer. I think it may have been due to improper sanitation while taking early samples so I really like the idea of sampling without opening the vessel and reaching in there, but if the keg is under pressure, how are you taking samples?
1. Picnic tap ? wouldn’t this give a bunch of foam?
2. Some other method?

###############Serving from the same vessel###############
I understand the transfer process to separate keg for serving which is cool, but i currently have very few kegs and i promised my family to keep at least one filled with soda water, so that limits my space even further. For those that are fermenting and serving in the same vessel:

1. do you bend dip tube?
2. Tilt the keg with a shim or something to draw the trub away from the dip tube?
3. cut the dip tube? I have one keg with a straight tube, and one with a bend, so is there an ideal length?
4. use a floating dip tube/cask widget? I really like this idea.
- Has anybody made a DIY version of this? I can figure out the dip tube and flex tubing part, but not sure what to use for the float and screen filter?



Thanks again for any help with this and sorry again if this is redundant. I will keep trying to access the Wiki as i am sure there is lots of other good info in there as well.

I've done DIY cask widgets.
"5 Pc Stainless Mesh Homebrew Inching Siphon Filter For DIY Brew Beer Wine Making"
https://www.ebay.com/itm/371835536084
First type I had to use two of these to get enough force that it wouldn't get caught on the side of the corny keg:
Pool MINI Liquid Vertical Water Level Sensor Float Switch Stainless Steel 45m
https://www.ebay.com/itm/302173503003
Next ones I make will use a slightly larger float:
NEW 1PCS Stainless Steel Water Level Sensor Float Ball 45mmx56mmx15mm
https://www.ebay.com/itm/NEW-1PCS-S...e=STRK:MEBIDX:IT&_trksid=p2057872.m2749.l2649

used a zip tie to clamp the silicone hosing to the little filter gizmo, since its diameter was a little on the large side and the silicone had to really be pushed on. I was afraid it might push itself off. Might look for a plastic or stainless clamp instead for the next ones, but I was trying to conserve weight the first time around.

Also, used stainless steel wire to attach the floats to the filter. A fine gauge stainless wire would go right through the mesh of the filter, and then around through the center hole in the stainless steel float.
I stacked them so the filter was on the bottom, on its side, when at the bottom of the keg, with the stainless floats on top. That way, it stays under the liquid level and has the best opportunity to not leave any beer behind, since the pickup tube in the filter lies on its side at the bottom.
There's a natural bend in the silicone tubing, so if you use a gas dip tube on your liquid out, simply push the silicone tubing over it and let the natural bend in the silicone tubing go to the opposite side of the keg.

Here's a thought that I think hasn't been discussed before. It starts from the idea that some people have been doing customized corny lids (for example, to put in an aeration stone or thermowell). I think most of those are relatively simple, putting a hole in the lid and adapting some fittings.

But what if someone could do a really customized lid, to include a conical section and ball valve? Picture this - after pitching your yeast, you invert the keg, and use the liquid out dip tube to vent off the CO2 produced during fermentation (since the end of the dip tube would now be up in the headspace above the liquid). When you've reached FG, you drain the trub through the valve on the new conical lid, then disconnect your vent line from the liquid out post, and put the keg back upright in its normal position for serving. Even more assurance that the beer has never seen O2.

I realize that the corny lid is pretty small, and it doesn't cover the whole width of the keg, so maybe it couldn't collect enough trub to make it work. Is that right? Or is there a potential opportunity here to get even more functionality out of our humble corny keg?

half a million views; what a thread. I'm intrigued reading the 57 pages, but then after reading a few of the recent posts I wonder if I really should.
Instead, let me be the bearer of bad news: You are wasting your time and money!
At least when it comes to the part of pushing sanitizer or the like through a keg to remove O2. It seems to be one of those myths. Reality is CO2 is heavier than air/O2.
Purge the keg for a minute with CO2 and you are fine!
The gas post is good enough, but for those who think the more work involved the better, feel free to use the liquid post while keeping the pressure valve open.

chris000 said:

Instead, let me be the bearer of bad news: You are wasting your time and money!

Click to expand...

Actually it is you who is misinformed.

But let's start with the only correct thing in your post: CO2 is heavier than air. That is true, but gases mix. They don't separate by density. Blasting tank CO2 into a keg is just going to swirl everything around and get it mixed up. You will certainly dilute the air in there, but not enough.

If you're happy with the method you do that's fine, but the techniques described on this thread have been developed and analyzed with much thought and scientific reasoning.

schematix said:

Actually it is you who is misinformed.

But let's start with the only correct thing in your post: CO2 is heavier than air. That is true, but gases mix. They don't separate by density. Blasting tank CO2 into a keg is just going to swirl everything around and get it mixed up. You will certainly dilute the air in there, but not enough.

If you're happy with the method you do that's fine, but the techniques described on this thread have been developed and analyzed with much thought and scientific reasoning.

Click to expand...

+1

Some chemistry guru did the math on another thread (can't find it at the moment) where he concluded that you would need to CO2 purge and release 16 times before all of the oxygen would be evacuated. That's just too much CO2 to waste IMHO.

Additionally there are other benefits to pressurized fermentation like grain to glass in as little as 1 week.

How long are we going to have to endure this myth that CO2 and oxygen settle out into different layers?

a) I'm not debating fermentation
b) sure it's true that it is a dilution, question is how much is enough?

so, if you believe in homeopathy you definitely need to fill it to the absolute brim with water.
otherwise, it is a fair question.

just 3 little facts, any homebrewer can try out
it takes mere seconds to get the "mixture" below the point where it doesn't support a flame any longer
if you keep the keg open after it sat in there for a while, to no ones surprise, the 1.5x heavier CO2 doesn't mix back into the air.
it should be obvious that beer will only come into contact with the lowest layer of that "gas-mixture"

so unless one prefers to assume a perfect mixture for ease of calculation (instead of a gradient) or uses a spray ball to transfer beer (no comment), the question is how many % of O2 are in the VERY BOTTOM of this 2 feet of gas column?

since some of you seem to have all the scientific reasoning, please feel free to share, because the beauty of science is that we all be allowed to be wrong at some point or another

chris000 said:

b) sure it's true that it is a dilution, question is how much is enough?

Click to expand...

Top limits for oxygen in beer is around 150 parts per BILLION. Roughly an ounce of air in a keg will get you there.

chris000 said:

it takes mere seconds to get the "mixture" below the point where it doesn't support a flame any longer

Click to expand...

16% oxygen maintains a flame.

chris000 said:

if you keep the keg open after it sat in there for a while, to no ones surprise, the 1.5x heavier CO2 doesn't mix back into the air.

it should be obvious that beer will only come into contact with the lowest layer of that "gas-mixture"

Click to expand...

This would come as a great surprise to many because this is utter non-sense.

chris000 said:

so unless one prefers to assume a perfect mixture for ease of calculation (instead of a gradient) or uses a spray ball to transfer beer (no comment), the question is how many % of O2 are in the VERY BOTTOM of this 2 feet of gas column?

Click to expand...

Non-sense.

chris000 said:

since some of you seem to have all the scientific reasoning, please feel free to share, because the beauty of science is that we all be allowed to be wrong at some point or another

Click to expand...

What you are spouting off isn't science, it's non-sense. You are arguing facts that have been known for hundreds of years.

@ schematix
1.
to do what?
e.g. you need 14 000 ppm O2 to produce 25 ppm acetaldehyde (taste threshold is 4-5x of that) and about 25 ppm O2 to get from there to acetic acid (700ppm threshold), and yes there are some acids with a very low taste threshold.
and that all does NOT happen instantly, it takes time and temperature.

2.
it has to be <12% to extinguish a flame right away, but good on you to make an attempt and look it up

3.
perhaps to those you have never filled a keg through a dip tube.
there is also dissolved CO2 in the beer that can create a foam which additionally acts as a barrier

4.
so, you don't know. and that' fair. some people even confuse CO and CO2 (one mixes well with air, the other settles), but calling everything you don't understand nonsense might not

5.
your 'argumentation' reminds me of 'long known facts' like the earth is a disc and the sun revolves around the earth and it is unhealthy to question those 'accepted myths'

the question is still how much oxygen is bad and why?
the defining criteria is taste and that is not objective!
I cannot understand who people drink (even pay for) sour beer, any notable level of acetaldehyde or diacetyl. why some brewers knowingly cause HSA. and why corona sells (well, I have a theory for that).
But why do I not have a black and white approach on O2?
Because just transferring beer from one keg to another doesn't oxidize it instantly. Considering that I keep nothing longer than 2 months in the fridge (just not enough space), gassing alone was completely sufficient.
PS: There are actually some publications on how much oxydation the average beer drinker prefers.

@chris000

Sounds like to have learned everything there is to know in regards to home brewing.

Dilly Dilly ...

Being serious now, with your questions on how much oxygen is bad and why... HSA is real. It is discussed sanely over at the low oxygen website.

If you always want to argue then start a thread here on HBT.

1MadScientist said:

Being serious now, with your questions on how much oxygen is bad and why... HSA is real. ....

Click to expand...

the HSA reference was with respect to people (who are commercially very successful) doing it on intention and making it a trademark. never said it would not exist (I just don't like it), but some apparently do...

Yes chris000 you are right on all accounts. I have idea what I’m talking about. But sounds like you do, so carry on.

arrasmithf said:

Hello to everyone and thanks for the great posts. i am new to the forum and this thread. I’m definitely interested in this type of fermenting as i have some tight space requirements and would like to either dual purpose my keezer as fermenting chamber, or be able to use higher ferm temps under pressure and use another space i have available with less temp control. I tried to access the wiki linked on the first page but i get a blank screen from both iPhone and a iMac. If its ok, can i get some clarification on a few points in the process?

###############Keg Filling#################
How high is best practice?
I have read some posts where low volume was used(4.5 gl) and a blowoff until after high krausen, and others that say fill up to the weld and pressure will keep the Krausen limited to 1cm.

###############Pressure###############
I read minimum 5psi to start/ maintain seal to no more than 25 psi, but is there an accepted schedule of ramping pressure from low to high during fermentation to reach carbonation at finish time?
Also, how does this relate to ferm temperature? Is process something like this(with typical fermentation)?:

Days
1———>2———>3———> 4———>5———>6———>7———>8———> 9———>10

5psi —> naturally build to 15psi —> hold w/ spunding—> ramp to 25 ——> chill and serve

65F ———————> Ramp schedule to ~70-72 ———————>Diacetyl rest ——>Finish


###############Temperature###############
I read Brulosopher’s blog post comparing ~60F temp to a ~80F temp under pressure with no perceptible difference, but not sure if that is OK in working practice.
1. How high of temps do you/can you run with a typical ale yeast? or Lager?
2. Any experience with the White Labs WLP925 High temp Lager yeast? There are many recipes i would like to try with this yeast so I would love to hear your impressions of it.

###############Dry Hopping/Flavoring###############
How to access the pressurized keg to add flavor?
1. Dry Hops/Flavor added immediately to wort. ingredients stay in keg entire time?
2. Depressurize, add flavoring, re-pressurize with CO2? doesn’t this defeat the purpose of staying oxygen free?
3. some other method?

###############Sampling###############
I had one infection in one of my first brews and it was a real bummer. I think it may have been due to improper sanitation while taking early samples so I really like the idea of sampling without opening the vessel and reaching in there, but if the keg is under pressure, how are you taking samples?
1. Picnic tap ? wouldn’t this give a bunch of foam?
2. Some other method?

###############Serving from the same vessel###############
I understand the transfer process to separate keg for serving which is cool, but i currently have very few kegs and i promised my family to keep at least one filled with soda water, so that limits my space even further. For those that are fermenting and serving in the same vessel:

1. do you bend dip tube?
2. Tilt the keg with a shim or something to draw the trub away from the dip tube?
3. cut the dip tube? I have one keg with a straight tube, and one with a bend, so is there an ideal length?
4. use a floating dip tube/cask widget? I really like this idea.
- Has anybody made a DIY version of this? I can figure out the dip tube and flex tubing part, but not sure what to use for the float and screen filter?



Thanks again for any help with this and sorry again if this is redundant. I will keep trying to access the Wiki as i am sure there is lots of other good info in there as well.

Click to expand...

Is this thread the most popular thread here? What a great wealth of knowledge. I was hoping arrasmithf had received answers but the conversation seems to have been high jacked about oxygen and CO2.

I want to start this process and have very similar questions as arrasmithf. arrasmithf, have you figured this process out yet?

My main questions (as well as arrasmithf's questions) are:

1. Can I use a 5 gallons Corny keg? Or is there not enough head space and I need to ferment in 2 kegs?
2. How to dryhop?
3. How long can hops stay in? Or do I transfer to a third keg?
4. How do you not transfer the trub to get clean serving beer?

I'm sure these have been answered. Forgive me for not readying 11 years worth of info! I've read most of it but still a bit confused on the full process.

I appreciate the help!
Lorne

I’ll give you my take on Q1 & Q4. I’m not a dry hopper so I’ll leave Q2 & Q3 to someone else.

You can certainly ferment in a 5 gallon keg.
Following schematix’s lead, I have successfully filled to the weld line with lager yeast.
Ale yeasts, I only fill with 4.5-4.75 gallons.

To leave trub behind, I bend the dip tube so that a half gallon is left in the fermentation keg.
Empty keg, open the lid, pour in 1/2 gallon of water.
Remove beer out post so you can remove/replace the diptube, bending/straightening it until it’s at the surface.

I measured the trub from a handful of bucket brews and found that my trub was always within 1.25 qt and 1.75 qt.
2qt left behind means I never see any trub in the transfer.

This means you’ll end up with 4 gallons of beer in the serving keg (4.5 gal - 0.5 gal).
Every time I kicked a keg, I kicked myself knowing I could’ve had another gallon of beer with a larger fermentation vessel.
So I paid out the nose for a pair of 10 gallon corny kegs.
I now get 5 gallons of beer in each serving keg.

Even though I have written on doing primary fermentation in a corny keg, and been successful at it, their are a few major drawbacks:

1. Final serving keg won't be full. You can easily get 4-4.25 gallons with an ale and 4.5-4.75 gallons with lagers though.
2. Dry hopping is tricky since there is 0 margin for error with regards to clogging poppets / dip tubes. I bag the hops and clamp the bag to the thermowell in my lid. I believe it would be possible to put a ring clamp on the PRV bump and tie off the bag to the ring clamp, but i've never tried it.
3. Cleaning corny kegs is a hassle.

There are advantages though...
1. They are made from high quality stainless (!)
2. They are super cheap
3. If you move on from using them as a primary they can easily be converted back to standard serving kegs
4. They are pressure capable to ridiculous levels one would never even need to consider using.
5. Built in dip tube for racking in a closed system.

All in all, they are vastly better than buckets and carboys. But if you have the money for a conical that's the way to go. I still use the corny kegs but i'd guess within a year I will have a single conical with a chiller. That will let me get that 10% batch reduction back and not have to deal with cleaning 2 of everything.

Have you guys tried the floating dip tube?

I Initially worried about transfers and trub and dry hopping, but after more research and some testing of my own, I went ultra simple. I ferment, dry hop and serve right out of the same keg. I use this.

https://www.morebeer.com/products/r...t-60-cm-silicone-dip-tube-fermentasaurus.html

It's a much cheaper version of that cask widget thing and it works great.My beers don't stay around for longer than a couple of weeks so I'm not worried about autolysis or oxidation issues. I get a more efficient use out of my kegs this way(fermenting multiple beers at same time) with less cleanup. since I fill to the seam with lagers or ales I make sure to remove the gas valve and run a blow off tube for the first couple days. Then I throw on spunding valve and let it finish.