How has Brulosophy changed your brewing habits?

[balrog]

People need to experiment on their own. When Marshall first started his blog, I had hopes that is what would happen, but people just took it a new dogma without recreating the study.

They do bring up good topics to think about, and try.

And listening to Marshall at NHC, I actually felt like his biggest goal was to get others to experiment

^+∞

He has made me want to try w34/70 at low 60's; try and like and stick with dumping everything into fermenter. My beer making mentor had already told me roiling boil is enough, volcanicly erruptive boil is not needed, and since it worked for me, I stuck with it.

Like many things I read, if supported by examples, I will try them myself.

 

[betarhoalphadelta]

I actually STRONGLY believe that fermentation temperature matters, and in the other thread was the one who ended up doing a meta-analysis of the Brulosophy exBeeriments on fermentation temp to show that despite many of them not achieving statistical significance individually, that a meta-analysis suggests fermentation temp to be a highly significant variable.

But how has this affected my own homebrew?

Well, when doing lagers with W-34/70 (my preferred lager strain), I've gone from fermenting at 49 and then raising temp a D-rest when fermentation slows to starting the temp at 49 and raising it a few degrees every few days over ~10 days, more of the quick-lager method.

So despite my own belief that fermentation temp is highly significant, and despite a meta-analysis that suggests the Brulosophy exBeeriments show it to be highly significant, I've relaxed my own lager method to more approximate his "quick lager" method.

 

[Die_Beerery]

I actually STRONGLY believe that fermentation temperature matters, and in the other thread was the one who ended up doing a meta-analysis of the Brulosophy exBeeriments on fermentation temp to show that despite many of them not achieving statistical significance individually, that a meta-analysis suggests fermentation temp to be a highly significant variable.

But how has this affected my own homebrew?

Well, when doing lagers with W-34/70 (my preferred lager strain), I've gone from fermenting at 49 and then raising temp a D-rest when fermentation slows to starting the temp at 49 and raising it a few degrees every few days over ~10 days, more of the quick-lager method.

So despite my own belief that fermentation temp is highly significant, and despite a meta-analysis that suggests the Brulosophy exBeeriments show it to be highly significant, I've relaxed my own lager method to more approximate his "quick lager" method.

I have honestly never understood this "fast lager" stuff. I pitch and ferment my lagers at 45F, they are ready to be spunded on day 5, and on day 7 I am at FG AND fully carbed, all in a fashion that avoided any oxidation. So I don't get it.

 

[applescrap]

Based upon Brulosophy experiments I've implemented the following changes already, and there will be more:

1) After reading the experiment wherein testers could not tell the difference between a lager bitter hopped (60 min boil) with Saaz vs. a lager bitter hopped (60 min boil) with Magnum, I have begun bitter hopping with magnum as my 60 min boil bittering addition to save money.

2) After reading the experiment wherein the testers could not tell apart a lager made with Maris Otter from one made with Pilsner malt, I went out and bought a 25 Kg. bag of Pilsner malt to use as my base malt for a broad range of styles.

3) I've cut back on my boil vigor.

As I've just started to implement these changes over my past 3 brew sessions, time and my taste buds will tell if I ultimately agree with Brulosophy on the above, and eventually on other of their experiemnts.

I am sure I have already made it clear, but I am willing to base/change pretty much all of my Brewing practices on many of these experiments. I never had a pony in this race and I am amused, frustrated and confused by how threatened some brewers get when their brewing dogma is questioned.

 

[applescrap]

I see now where i accidentally conflated and confused the two of them, and the one I intended was this one:

http://brulosophy.com/2017/08/28/gr...lt-2-row-vs-pilsner-malt-exbeeriment-results/

The test in which there was no statistical difference detected was the one between 2-Row and Pilsner, and not between Maris Otter and Pilsner, and I stand corrected.

What impressed me in the first one was that even though a difference between 2-Row and Maris Otter was easily statistically detected, in the end 10 testers who could tell a difference preferred Maris Otter and 10 testers who could tell a difference preferred 2-Row Brewers, so among them it was a dead even split as to preference. So if there is no statistical palate difference between Pilsner and 2-Row, one would expect an even split between Pilsner and Maris Otter preference as well. And lastly, even the person conducting the experiment commented that a lot of microbreweries could back off of more expensive Maris Otter and go with 2-Row without a majority of their customers ever noticing the change.

This kind of thinking has been for the most part, my main point. In a lot of these tests the differences to me arent big enough, even when statistically present, coupled with preference data, annecdotal data and tester impressions to warrant me really caring one way or another so I lean toward convenience and ease generally.

 

[ericbw]

I am sure I have already made it clear, but I am willing to base/change pretty much all of my Brewing practices on many of these experiments. I never had a pony in this race and I am amused, frustrated and confused by how threatened some brewers get when their brewing dogma is questioned.

I guess I'm curious why you're so convinced of their validity. Why do invested. Just wondering.

 

[applescrap]

I guess I'm curious why you're so convinced of their validity. Why do invested. Just wondering.

I really appreciate the question and man oh man do I have a really great answer, but honestly in the words of a very cool hbt member, this rabbit hole is just to deep to go down. It is clear to me that people will believe as they wish and thats ok.

 

[stickyfinger]

The biggest impact in me is I’ve done a few of my own exbeeriments finally. I too realized how difficult it is to tell the difference between certain beers, even when I knew the variable.

 

[Silver_Is_Money]

As an incessant tinkerer I don't believe that I have ever brewed the "exact same" recipe twice. Every beer I brew is therefore an experiment. I would actually find it boring to repeat a recipe exactly to the N'th degree. No challenge in it.

 

[stickyfinger]

As an incessant tinkerer I don't believe that I have ever brewed the "exact same" recipe twice. Every beer I brew is therefore an experiment. I would actually find it boring to repeat a recipe exactly to the N'th degree. No challenge in it.

That is the exact opposite of an experiment! ha ha i hear you though. i like doing something different most of the time.

 

[MSK_Chess]

I also did the 50 attenuation lager and it was ok. My beers have improved dramatically though since I started paying close attention to oxygen ingress both hot and cold side.

 

[mongoose33]

As an incessant tinkerer I don't believe that I have ever brewed the "exact same" recipe twice. Every beer I brew is therefore an experiment. I would actually find it boring to repeat a recipe exactly to the N'th degree. No challenge in it.

This is not to be argumentative, but rather to explore differences in philosophy.

My son never seems to brew the same beer twice. I don't know if he's on a search for the holy grail, or is one of those people who don't want sameness. A buddy of mine is a fairly prolific rater on RateBrew. Approaching 600 ratings. I don't recall, in the last 10 years, seeing him drink the same beer twice in a row.

I'm the opposite of both of them. I want to refine recipes, making them perfect, or as close to perfect as I can approach. When I brew a good beer I want to tweak it, make it really good, or even, dare I say, great! Maybe I'll get there.

And when I hit on one, that beer goes into rotation. I have 5 recipes that are repeaters; I might on a whim tweak 'em a bit, but I like them, others like them, why would I fool with something that's a hit?

**********

Again, like my buddy, perhaps your approach is one of always wanting something new. But I also see people who don't seem to want to refine anything in brewing, and I wonder why. I wonder if there's maybe some cognitive dissonance going on, i.e., if one always brews something new, one can always dismiss a less-than-excellent result as a consequence of the recipe, or a different fermentation or mash schedule, or whatever. What cannot be easily critiqued is the process or the brewer's skill, as the variation in recipe precludes that. Beer didn't turn out? Is it the recipe, or the process?

I've followed a strategy of continuous quality improvement, i.e., every time I brew I try to do something better than last time. I'm trying to create beer that, when others try it, their response is "Wow!". I wonder if others who are always changing things are concerned they won't be able to show improvement with a repeat, will reveal problems in the process that are covered up by always changing things.

Not saying that should be anyone's goal. It's my goal, but just that. No one else has any obligation except to whatever goals appeal to them. My buddy doesn't like to drink the same beer twice, so no reason why anyone should feel obligated to brew the same beer twice.

 

[jack13]

As an incessant tinkerer I don't believe that I have ever brewed the "exact same" recipe twice. Every beer I brew is therefore an experiment. I would actually find it boring to repeat a recipe exactly to the N'th degree. No challenge in it.

----

That is the exact opposite of an experiment! ha ha i hear you though. i like doing something different most of the time.

That exchange describes my problem.

I'd like to be able to see the effect of one variable (let's say doing a cream ale with vs. without rice), that is, do an experiment. But inevitably, I'd also end up varying other things, too (mash temp, boiled a little longer, hops weren't as fresh and, oh yeah, I've switched from a bazooka tube to a false bottom since then).

It would actually be much more of a challenge to exactly duplicate a brew than to redo it pretty much the same.

 

[mongoose33]

----



That exchange describes my problem.

I'd like to be able to see the effect of one variable (let's say doing a cream ale with vs. without rice), that is, do an experiment. But inevitably, I'd also end up varying other things, too (mash temp, boiled a little longer, hops weren't as fresh and, oh yeah, I've switched from a bazooka tube to a false bottom since then).

It would actually be much more of a challenge to exactly duplicate a brew than to redo it pretty much the same.

I'm a scientist, let me weigh in a bit here. You're much closer to being able to do a good experiment than you might think.

Part of the process of doing this is in how you prepare. You already understand the main issue in experimenting like this, i.e., isolating the single variable of interest. You understand the problem of having alternative explanations (temp, boil, hop differences, etc.) of a final difference, i.e., was it the variable of interest that caused a result, or one of the other explanations?

Just did an experiment last weekend, comparing a single change. I'll report on it somewhere here when I have results, but my goal was the same as yours--two batches exactly the same except for the one variable of interest.

So I planned for that. Two batches brewed in succession. I can't do them simultaneously, which was a concern, but I did everything I could to make them identical. Same hops from the same lot. The grain was from the same lot. I crushed the grain in both cases 45 minutes before dough-in. My mash temp differed by about .7 degrees F, the pH of the mashes were 5.31 and 5.28 (and the difference might have been related to the variable of interest).

Boiled the exact same length of time, laid out and did hop additions at the same times. I used two packs of WLP001 in a 2-liter starter, which I split evenly between the batches when i pitched. My OG for one batch was 1.062, the other about 1.0615.

They are not exactly the same. As you note, that's very difficult to do. I wish I had batches were the variable was, say, a difference in yeast, because i could have split the batch and I'd know up to that point they'd be identical.

But the variable of interest goes in the strike water, so that's impossible.

**************

So here's the question: are my two batches close enough that there is fundamentally no difference in them due to basic recipe and technique? Is it likely we'd be able to discern a difference between 1.062 and 1.0615? Or between mash pH of 5.31 and 5.28? Or mash temp difference of .7 degrees?

I would not expect those two batches to show a difference, if I'd brewed them w/o the variable of interest. So if there's a detectable difference at the end, I will tend to attribute it to the variable, not the slight differences in batches.

Could these minor variations account for the difference? Sure, it's possible, but I have to accept them as being the same. I don't have any particular expectations for the variable of interest--I'll accept the results as true and then, at some future time, try to replicate them.

I have several "repeat" recipes. I like them, others like them, so I keep brewing them. I've got a new one, Darth Lager, that was just delicious the first time (even a blind dog finds a bone once in a while). I couldn't share the recipe until I'd done it again, and I was able to do that. Big hit. Third batch is in the fermenter right now, but I've changed that one variable. I have the 2nd batch on tap right now so some level of comparison can be made. I'm hopeful, Morrey has brewed the same recipe with that variable included, and he says it pops. So I'm hoping to find the same thing.

My point is that you are far better positioned to do this than most might be. You understand the problem, i.e., one of control. And you can control most of the variation ahead of time. Use the same hop lot, keep them in the freezer until used. Same grain lot. Same everything, using notes to record and then again follow.

I suspect many of us have variability in how we brew not because we can't do things more precisely, but because we believe such minor variations don't matter that much. If you have a 30-minute addition and you do it at 29 minutes, do you expect to taste the difference? I don't. Same with a .7 degree difference in mash temp. Or a .03 difference in pH.

When I did my experiment last weekend I was as precise as I could be. I am not normally that precise when brewing. I suspect most aren't.

 

[jack13]

I'm a scientist, let me weigh in a bit here. You're much closer to being able to do a good experiment than you might think.

Part of the process of doing this is in how you prepare. You already understand the main issue in experimenting like this, i.e., isolating the single variable of interest. You understand the problem of having alternative explanations (temp, boil, hop differences, etc.) of a final difference, i.e., was it the variable of interest that caused a result, or one of the other explanations?

For me two things have prevented me from doing real experiments.

One is that it's a lot of work and prep, like you said, and my desire just isn't there (when I said "I'd like to see the effect of one variable..." i really meant it that way. I'd like to. Right now that's not the priority though)

Second is I'm still new enough to brewing that I'm making changes all the time, some of them un-change-back-able on brewday. My example of going from a bazooka tube to a false bottom was a real one (tube broke). And my LHBS is pretty small, so sometimes ingredients or other accoutrements aren't available, introducing other variables.

However, my methods are getting more consistent over time: I recently re-did a pumpkin ale I did last fall. I attempted to do it the same, at least without going to too much trouble, but in the end my list of differences between the batches numbered about 12. In comparison, I also recently re-did a cream ale, but the first time I did that one was only a few months ago. I also made a list of differences, and there were only about 4.

 

[applescrap]

Mino choi, the person I quote often brews the same batches over and over. This is no doubt a worthwhile venture to get a feel for brewing and Brewing practices.

 

[Bosh]

I've done a lot of split batches of my own inspired by their basic idea and changed things based on my beers rather than their beers since I can't taste their beers.

For example I've started using US-05 for most everything after prefering it again and again across different split batches.

 

[mattdee1]

Ive read Brulosophy only for the keezer build, but you are not inspiring my confidence in the experiments. Destroying brewing "dogma," "rules" and myths would take more than imperfect experiments. Investigating an experiment isn't "raining on a parade" and parsing through results is an important part of the scientific analysis. This game somewhat reminds me when naturopathic claims are investigated, the claims are iconoclastic yet when subjected to review, naturopaths attack "of course western medicine would want to destroy our claims," yet they purport to do the same to western medicine.

Cue "well its not science like that" or "its not purporting to be like that" or some other sort of response that tries to take the experiments outside the realm of science but yet regard the results as scientific enough. Enough so to destroy brewing "dogma," whatever that is.

I don't know what you're trying to say with your last paragraph; those sorts of disclaimers are exactly what one would put forth, because they reflect the reality. So what...? You seem to be saying "if you're not going to be an absolute paragon of scientific rigor Mr. Brulosopher, then GTFO." Why? It's just a guy having fun and sharing his exploits on a hobbyist blog. You're just as free to ignore it as others are to gobble it up. Sanctimonious lectures about the blog's lack of adherence to the scientific method are completely unnecessary, because the limitations of the methods are openly acknowledged.

 

[applescrap]

I would like to say that Marshall has brewed and brews waaay more beer than me (think most), has met with more famous hb people, worked harder at hb, invested more time in hb, blogged about hb, written wonderfully about hb, experimented with hb, used different equipment in hb than me by 100x over. In totality, his work in home brew is down right impressive imo.

 

[mongoose33]

For me two things have prevented me from doing real experiments.

One is that it's a lot of work and prep, like you said, and my desire just isn't there (when I said "I'd like to see the effect of one variable..." i really meant it that way. I'd like to. Right now that's not the priority though)

Second is I'm still new enough to brewing that I'm making changes all the time, some of them un-change-back-able on brewday. My example of going from a bazooka tube to a false bottom was a real one (tube broke). And my LHBS is pretty small, so sometimes ingredients or other accoutrements aren't available, introducing other variables.

However, my methods are getting more consistent over time: I recently re-did a pumpkin ale I did last fall. I attempted to do it the same, at least without going to too much trouble, but in the end my list of differences between the batches numbered about 12. In comparison, I also recently re-did a cream ale, but the first time I did that one was only a few months ago. I also made a list of differences, and there were only about 4.

Makes sense--and at least you're getting better at it!

It took me a while to nail down the process so it would be repeatable. Some of that was adding new things (oxygenating the wort, for instance), some was organizing my brewspace.

I helped a friend get into brewing. The second time we did it, he took detailed notes about when to do this/that/the other things. He still made goofs when he did it on his own, but he's now doing pretty well after about...oh, 7 or 8 brews.

If you're not doing it very often, that can make it hard to nail down a consistent process.

 

[ericbw]

I would like to say that Marshall has brewed and brews waaay more beer than me (think most), has met with more famous hb people, worked harder at hb, invested more time in hb, blogged about hb, written wonderfully about hb, experimented with hb, used different equipment in hb than me by 100x over. In totality, his work in home brew is down right impressive imo.

Everything you say is interesting. He's done a lot of work. That's extensive. To be impressive, it seems like the results should be less impeachable. It's not that people don't think he's putting in the work. It's that the results are far from clear.

I think that's the divide - those who see the results as definitive and those who see it as interesting but not conclusive.

 

[betarhoalphadelta]

I should point out that you don't need to re-brew the same recipe over and over to judge your own process.

I would think that it's harder, of course, if you're changing all sorts of different recipe factors from batch to batch.

But for a lot of beers, there really isn't a lot of complication. If I'm brewing a blonde ale, or an Oktoberfest lager, or even an IPA, I know based on the ingredients going in what it's "supposed to" taste like.

Granted, if you decide you want to brew a peanut butter milk stout, follow that up with a grodziskie, and then a gruit, it's hard to gauge your process. But if you're brewing more "classic" styles, it's not that hard.

 

[jack13]

Mino choi, the person I quote often brews the same batches over and over. This is no doubt a worthwhile venture to get a feel for brewing and Brewing practices.

That is undeniably true.

 

[MSK_Chess]

I would definitely say they ave changed my approach to the amount of time taken from pitching to Keg. Before it was two weeks fermentation and two weeks conditioning. Now its like as soon as fermentation has finished get it chilled, fined and in the keg.

 

[ericbw]

I would definitely say they ave changed my approach to the amount of time taken from pitching to Keg. Before it was two weeks fermentation and two weeks conditioning. Now its like as soon as fermentation has finished get it chilled, fined and in the keg.

Even when I do that, it still takes 4 weeks to taste good.

 

[Upthewazzu]

Even when I do that, it still takes 4 weeks to taste good.

I sort of agree. Something magical happens 2 weeks after kegging. This is true of all the styles I make.

 

[RichBenn]

Oh boy...another one of these threads. Lets see how it takes to derail like the other one.

In support of the thread I like reading his exbeeriments. I did the 34/70 warm quick lager that worked out well....if nothing else his exbeeriments have made me worry less about my brewing

I did an accelerated Octoberfest for a party using 34/70 because of Bulosophy and it is as good as the best Marzen I've ever had. Your worry less comment is right on. RDWHAHB is rediscovered!

Oh, and please, people, there is another bash brulosophy thread. Let`s keep this one on point. All of us that have been brewing for a while(since '81 for me) have incorporated changes in our brewing from others experiences including myths we now no longer follow - and this thread is asking for examples of that based on Brulosophy.

 

[schematix]

I would definitely say they ave changed my approach to the amount of time taken from pitching to Keg. Before it was two weeks fermentation and two weeks conditioning. Now its like as soon as fermentation has finished get it chilled, fined and in the keg.

Even when I do that, it still takes 4 weeks to taste good.

I look back and laugh now that when i first started i did a 28 days primary as standard practice.

Now by day 14 i'm in the keg, fully keg conditioned, and chilled already for a few days. The beer is much better for it.

 

[Murphys_Law]

I’m not sure there is any one thing that’s changed but my take away is that beer can be pretty forgiving. As a home brewer I want consistency but if one batch varies slightly over another...it’s still good beer, just different.

I can live with that (unlike professionals who need to have consistency).

 

[ericbw]

I’m not sure there is any one thing that’s changed but my take away is that beer can be pretty forgiving. As a home brewer I want consistency but if one batch varies slightly over another...it’s still good beer, just different.

I can live with that (unlike professionals who need to have consistency).

I think that's one of the things I think is interesting/good about home made stuff. There's a variation.

 

[ericbw]

I look back and laugh now that when i first started i did a 28 days primary as standard practice.



Now by day 14 i'm in the keg, fully keg conditioned, and chilled already for a few days. The beer is much better for it.

So you're "grain to glass" within 3 weeks? Does it improve with time after that?

 

[schematix]

So you're "grain to glass" within 3 weeks? Does it improve with time after that?

I call it 2-3 weeks. I like the extra week of just pure cold storage to drop the beer bright. The IPA is better at 2 weeks than 3 weeks though.

Over time I've found that if you do everything right up front, it's basically at its peak as soon as its done. There's no aging required.

Lagers however do get better for about 4-6 weeks before they plateau.

 

[JONNYROTTEN]

I call it 2-3 weeks. I like the extra week of just pure cold storage to drop the beer bright. The IPA is better at 2 weeks than 3 weeks though.

Over time I've found that if you do everything right up front, it's basically at its peak as soon as its done. There's no aging required.

Lagers however do get better for about 4-6 weeks before they plateau.

This is the reason I'm going to filter my next batch. THe beer is done but the yeast takes awhile to drop out and takes away from the flavor. Looking forward to seeing how it works out. Never know might have clean fresh beer ready to drink in 10 days

 

[schematix]

This is the reason I'm going to filter my next batch. THe beer is done but the yeast takes awhile to drop out and takes away from the flavor. Looking forward to seeing how it works out. Never know might have clean fresh beer ready to drink in 10 days

If you think yeast takes out the flavor, wait until you try filtering. Very bright beer though. Short shelf life though due to oxidation.

 

[ircbrewing]

I also do a 14 day schedule. I let the beer go in the bucket for 14 days and then keg and set psi to 25 psi for 3 days and its done. 17 days. The carbonation is really set after 4-5 days at serving pressure but plenty drinkable after 3 days at 25 psi.

I can do a centennial blonde ale in 7 days and 3 day carb so its ready in 10 days but its a light grain bill and doesnt take long for US-05 to plow through it.

 

[Miraculix]

I call it 2-3 weeks. I like the extra week of just pure cold storage to drop the beer bright. The IPA is better at 2 weeks than 3 weeks though.

Over time I've found that if you do everything right up front, it's basically at its peak as soon as its done. There's no aging required.

Lagers however do get better for about 4-6 weeks before they plateau.

Let's add Stouts to the list of brews that benefit a lot from longer time on the yeast.

 

[JONNYROTTEN]

If you think yeast takes out the flavor, wait until you try filtering. Very bright beer though. Short shelf life though due to oxidation.

I've heard about oxidation with filtering but I'm having a hard understanding why. I've been using an auto siphon for years without issue. My plan is to use a small brown pump to push through an under sink filter. Aside from the churning of the pump possibly adding oxygen I don't see the difference. Don't people use a pump to transfer instead of an auto siphon without issue?? It's just moving beer from point A to point B with a filter in the middle. I read mixed reviews on stripping flavor. Shelf life never seems to be an issue around here

I was actually thinking of racking to keg with an auto siphon my normal way and hooking up to system. Then attach a tube to the end of my faucet and filter to another keg just like pulling a tap. It's a bit of a stretch and a double transfer but being is being pushed with co2 I thought it might not be an issue ???

 

[thunderwagn]

Read that too....I wanna try this....so you fermented in the 60's?

Worked well for me fermenting a helles. 34/70 pitched at 58 and free rise up to 68. Rack to keg with gelatine and lager in fridge for several weeks.

 

[ircbrewing]

Agree stouts do not really apply I think. They could use a good month to really age approptiately. That said Ive dont plenty good ones on the 14 day schedule.

 

[mongoose33]

I've heard about oxidation with filtering but I'm having a hard understanding why. I've been using an auto siphon for years without issue. My plan is to use a small brown pump to push through an under sink filter. Aside from the churning of the pump possibly adding oxygen I don't see the difference. Don't people use a pump to transfer instead of an auto siphon without issue?? It's just moving beer from point A to point B with a filter in the middle. I read mixed reviews on stripping flavor. Shelf life never seems to be an issue around here

I was actually thinking of racking to keg with an auto siphon my normal way and hooking up to system. Then attach a tube to the end of my faucet and filter to another keg just like pulling a tap. It's a bit of a stretch and a double transfer but being is being pushed with co2 I thought it might not be an issue ???

Why would filtering promote oxidation? If the filter is not purged of O2, as the beer is forced through the filter it's coming into contact with...air, and O2.

Anything that causes bubbles or other contact with air will give you exposure to O2. If you could purge the filter lines and filter housing w/ CO2 then filter the beer, I don't see any issue.

If I were inclined to do this (thinking out loud here), I might set up the lines and filter housing in series with the CO2 being produced in fermentation. I've included a pic below showing a system to preserve CO2 so that will be what's sucked back when I crash the beer in the fermenter.

The fermenter in the small fridge has a lid w/ just a small rigid plastic tube to which is connected 5/16" silicone tubing. That tubing runs through a drilled hole in the top of the fridge out into the left jar. As fermentation proceeds, CO2 is pumped into the first jar, then moves into the second where it's bubbling up. Not difficult to add tubing and filter in series with this so as to benefit from the natural production of CO2.