# Confused about lagering times and temperatures



## galactaphonic (25/10/14)

Hi all,

I hope this isn't a question that is constantly asked but... I'm confused about the lager process as there seems to be a lot of contradictory information out there. I think I get the primary fermentation part - roughly two weeks at about 10°C then a diacetyl rest - but I'm not 100% sure what to do next.

Here's some of what my research has turned up:

Palmer says "Nominal lagering times are 3 - 4 weeks at 45°F, 5 - 6 weeks at 40°F, or 7 - 8 weeks at 35°F". 
Wyeast say something different. What Palmer calls "lagering" they seem to refer to as secondary fermentation and "secondary fermentation can take from one to three weeks at temperatures starting between 39-41°F (4-5°C)". After this secondary fermentation comes the period that Wyeast call lagering or cold conditioning, is "generally in the range of 33-34°F (1-2°C)", and a "lagering period of one to four weeks is typical."
In the latest BYO magazine in the Style Profile section, Jamil Zainasheff says to finish all active fermentation at 10°C before doing a period of cold conditioning at near freezing temperatures for a month.
Then there's this guy with a very helpful step-by-step guide where he says to lager it at 45°F for 6 weeks. 

So far I've only finished one lager and it turned out fairly ester-y. I must say I'm not particularly keen on making all that effort if I'm only ever going to turn out substandard lager.

Can anyone help me link all this advice together?


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## MHB (25/10/14)

Couple of things, I for one couldn't be arsed converting from silly systems to metric, please post in metric.
This is from Kunze which is holy writ when it comes to Lager brewing



- - - Being SG
___ Thin Being Diacetyl in mg/L right hand scale
*___ *Thick being Temperature in oC from scale on left
Up Arrows, being where yeast/trub is cropped in days from pitching

This is the simplest temperature time profile for lager, it presupposes very large (by home brew standards) yeast pitches and pretty tight temperature control.

The whole point of lager brewing is to make beer with out too many sulphur based flavours, the cool fermentation reduces these.
Cleaner flavoured beer, Lager yeast eats some sugars that Ale wont, lower temps also reduce ester production but you need more yeast as it is working slower.
Lagering (literally to store from German) also called "Chill Proofing", "Cold Conditioning"... The idea being to allow tannins and polyphenols to combine (chill haze) and then give them time to fall to the bottom of the tank, to either remove them or rack the off them without allowing it to warm up. If it does warm up the chill haze will go back into solution and you will have undone all the lagering.

The colder you lager (above where the beer freezes) the faster the haze forms and the faster it falls out (relative density see Stokes law).
An old rule of thumb was seven days at -1oC, and seven days for every degree above minus one. so at 0oC we are looking at two weeks, at 2oC four and so on, that's just for the haze, flavour maturation may take longer.

Making really good lager is hard work, requires the right equipment (a fan forced fridge and a willingness to rack a couple of times at a minimum), it ties up your equipment for a long time and does demand patience, but if you like lager it can be fun and challenging.
Have fun
Mark


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## waggastew (25/10/14)

Something else to consider is slowly ramping down to lager temp rather than crash chilling. Aims to keep more yeast active and in suspension. A degree a day seems the suggested rate.


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## verysupple (25/10/14)

waggastew said:


> Something else to consider is slowly ramping down to lager temp rather than crash chilling. Aims to keep more yeast active and in suspension. A degree a day seems the suggested rate.


There might be a need to chill slowly and keep the yeast active if you're brewing to the reinheitsgebot - can't force carb. so you need the yeast to create the CO2 before filtering/packaging etc. But otherwise there's no reason not to follow something similar to the "holy writ" above. So long as the yeast has done everything it needs to do before you chill the beer you can chill it relatively quickly.

That said, there's been a bit of talk recently about the yeast expressing esters when heated or cooled too quickly. I did some digging in to this and it's apparently only an issue if you're chilling from fermentation temp to cold conditioning/lagering temps in less than about six hours - That's 1.67 C per hour assuming ferment temp of 10 C and CC temp of 0 C. My fermenting fridge won't manage that so I just set it to 0 C and forget about it.


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## indica86 (25/10/14)

I used this method http://brulosophy.com/methods/lager-method/ and it worked really well. 
Possibly I can't taste anything and have no idea. There was a bit of haze, but ALL my beers suffer from that.
It was clean, crisp and lovely.


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## manticle (25/10/14)

I have found a significant difference in diacetyl levels by cold pitching big active starters, warming slowly for d-rest 2/3 through ferment then chilling slowly to 1-2 degree ( as opposed to fast raise d-rest, fast drop to chill).
Pretty sure my results will improve further when I introduce pure oxygen, something I'd like to get going in the next few months.


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## galactaphonic (27/10/14)

Thanks a lot for the replies people. I also found this article which tied a lot of it together for me too.

http://braukaiser.com/wiki/index.php?title=Fermenting_Lagers

My takeaways are:

After fermentation is complete then keep at about 1-2°C for about four weeks
Primary fermentation can be hastened by a big yeast starter
Slowly ramping up and down temps is probably a good idea
The thing I wonder about, does the four weeks at near freezing actually do anything magical apart from just drop stuff out of suspension i.e is it really just an extended cold crash?


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## verysupple (27/10/14)

galactaphonic said:


> The thing I wonder about, does the four weeks at near freezing actually do anything magical apart from just drop stuff out of suspension i.e is it really just an extended cold crash?


Well, in practice it's a bit like a long cold crash - but minus the "crash" - slow ramps are probably better as you now know (but that applies to CCing ales, too). But it's the same in that you just keep the beer cold for a while. It does more than just drop stuff out. The flavour usually changes along the way even after it's dropped clear. I guess chemical reactions are happening slowly.


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## Mr. No-Tip (27/10/14)

MHB said:


> All the stuff MHB said


I agree on the whole, but I don't get the fan forced bit. A chesty works just fine?

Multiple rackings is a daunting way of putting it, we're really talking about once off the primary trub and once off the lager trub. If you lager in a keg, use a bent dip tube and it's really no extra effort when you go to bottling or kegging. Unless MHB means more racking than that?







galactaphonic said:


> Thanks a lot for the replies people. I also found this article which tied a lot of it together for me too.
> 
> http://braukaiser.com/wiki/index.php?title=Fermenting_Lagers
> 
> ...


I love the BK article. It's what I base my lagering off. For me a big yeast starter is essential. I do two in date White Labs into 3l for 20l of lager.


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## SnakeDoctor (27/10/14)

Mr. No-Tip said:


> I love the BK article. It's what I base my lagering off. For me a big yeast starter is essential. I do two in date White Labs into 3l for 20l of lager.



That's still under pitching for a medium OG lager isn't it?

I thought lager starters were all up around the 5L mark?


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## TheWiggman (28/10/14)

SnakeDoctor said:


> That's still under pitching for a medium OG lager isn't it?
> 
> I thought lager starters were all up around the 5L mark?


Depends on OG, batch volume, whether you use a stir plate, temp etc. I do 2.5l with a single pack for 23l of 5% and Mr Malty says that's fine. Without a stir plate it would be a different story.

Ed: actually I'm not so sure now. I just put it in Mr Malty and with a 1 month old pack of yeast -




It says I should use 2 packs of yeast (which I don't). My current practice is to do 1l to get it kicking, let it ferment out, then step up to 2.5l. From what I can tell this is an acceptable practice.


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## slcmorro (28/10/14)

SnakeDoctor said:


> That's still under pitching for a medium OG lager isn't it?
> 
> I thought lager starters were all up around the 5L mark?


From what I understand (and I am by no means an expert), it's still better than just dumping in a sachet/pack of yeast and hoping for the best. I collect the first runnings of almost every brew I do, and it sits refrigerated in a sanitised mason jar (1L), and then to that I add yeast be it liquid or dry. After 3 days (not scientific, I know) I usually dump the lot minus the decanted top layer of beer into a fermenter or if I have done another brew in the meantime or have DME available, I add more wort/DME to the mason jar for a further 3 days. 

Absolutely no idea how many cells will be in there by the end, but I do know there will be more than when I started. I also taste the beer on top before pitching, to ensure the yeast is un-compromised.


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## DJ_L3ThAL (28/10/14)

slcmorro said:


> From what I understand (and I am by no means an expert), it's still better than just dumping in a sachet/pack of yeast and hoping for the best. I collect the first runnings of almost every brew I do, and it sits refrigerated in a sanitised mason jar (1L), and then to that I add yeast be it liquid or dry. After 3 days (not scientific, I know) I usually dump the lot minus the decanted top layer of beer into a fermenter or if I have done another brew in the meantime or have DME available, I add more wort/DME to the mason jar for a further 3 days.
> 
> Absolutely no idea how many cells will be in there by the end, but I do know there will be more than when I started. I also taste the beer on top before pitching, to ensure the yeast is un-compromised.


I've only just started with the Yeast book by Chris White, but AFAIK, doing a smaller starter as you described might actually be detrimental as the inoculation rate is very low, so there is no room for growth given you have so many cells in the yeast vial. It's more of getting that balance right rather than a small starter or even going to a huge starter (ie. Straight into full batch size, which would then be stressful for the yeast).

But the crux of what i have taken from it so far is that you are far better pitching two vials (lager) straight into your 23L batch than you are in a 1L starter and then into 23L. As you essentially set the yeast straight into sugar eating mode and then when dumped into the full batch they need to switch back to growth phase. Balancing the starter size with the amount of yeast you have ensures correct amount of growth so that when in the main batch the yeast won't be stressed out and can just get on with the job in a clean fashion.

Bottom line is you need to read and understand it all, more so than going off a set few dot points people on here kindly share, as it's not always the entire picture.


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## rude (28/10/14)

The thing I wonder about, does the four weeks at near freezing actually do anything magical apart from just drop stuff out of suspension i.e is it really just an extended cold crash?

Funny you should say that Galactaphonic because the other day I had a munich dunkel brewed with a wyeast lager yeast
It was brewed with a williamswarner unit at my local LHBS it was very nice
The bloke told me that it was drinking at 13 days ofter fermentation due to it being under pressure clear as a bell
Ales only 7 days problem was the price of the unit
This got me thinking along youre lines above as well
Just thought I'de share but no idea on lagers really never brewed one but it is on the cards good thread for me cheers


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## MHB (28/10/14)

Drifting slightly off topic, but yeast management is integral to making good lager, so perhaps not too far OT.
Ideally we need a lot of health yeast if we want to pitch cold, unfortunately a lot of the methods mentioned here may give you a lot of yeast but I would question its health. One of the vital ingredients in yeast propagation is Oxygen, without the right balance of O2 and other nutrients the yeast can be very stressed and can produce beer that is seriously flawed.

Make a special starter wort at about 1.040 (give or take), use the recommended amount of nutrient, and aerate to 10ppm with O2. Starters should be stepped up 10X in volume and you should see a 6-8 fold increase in the population at each step. Do the numbers, work out how many cells you need and what you think you are starting with that will tell you how many steps you need. I wouldn't assume the maximum population increase (I use 6X) as the danger of over-pitching is dwarfed by the problems caused by under-pitching .
Personally I like to run the yeast through its full life cycle, Pitch, allow to complete fermentation and settle out, remove the top layer and add more well aerated wort, as many times as necessary to get the population I want.

It might sound a bit tedious, but that is what it takes to make really top quality Lager. Some time ago there was an article by the head brewer at Budvar that said they pitched 5L of heavy yeast crem/Hl, works out to about 64 smack packs in 20L, I don't seriously expect any home brewer (myself included) to have those sort of pitches available, but more is better when it comes to pitching lager yeast. 
Mark


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## GalBrew (28/10/14)

I agree 100% with MHB on pitching rates. Very important to pitch the appropriate amount of yeast (use a calculator) for lagers to be clean. That and an appropriate shot of oxygen. I can't see how you can make a clean lager without at least those two things.


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## TheWiggman (28/10/14)

With regards to O2 Mark I don't have a dedicated canister (yet). To address this I run the stir bar hard - as in, making sucking noises with a big vortex - for 10 mins after adding boiled DME/water at 1:10 to try to introduce as much as possible. Is this a decent alternative?

And based on your comments I should pitch the fresh yeast into a 250ml starter to begin with, and then to 2.5l.


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## manticle (28/10/14)

You need to oxygenate the main wort as well as the starter wort.


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## rude (28/10/14)

So MHB or anyone having a play around with some yeast calcs here Mr Malty & Yeastcalc ( has the step calc) for 25L 1050 lager using a stir plate
Mr malty says 463 billion cells for current date you need a 5.14 Litre starter using 1 pack wyeast
so only have 5L erlenmyer flask so go to step calc
This calc for the same above says 464 billion cells using the zainesheff stir plate so use the step1 you need 1.5 L
step 2 another 1.5 L after fermenting ccing & draining to give you 468 billion cells
Assuming I have used nutrients o2 would this method be satisfactory & why only a total of 3Litres in the step up
compared to 5 Litres in single
Hope I'm not too off topic cheers


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## DJ_L3ThAL (28/10/14)

You cant do a 1.5L, remove the top layer and add another 1.5L to the freshly grown yeast population. Youll get minimal growth. Each step needs to INCREASE in size.

E.g. 10mL yeast into 100mL wort. Then resultant yeast into 1L etc. Each step needs to have the balance between amount of yeast and volume of wort known as the inoculation rate to maximise the amount of growth you get whilst not stressing out the yeast.

A good rule of thumb example would be one reasonably fresh white labs vial (50% viable) straight into a 3L starter (on a stir plate) wort for a 23L batch at 1.050. This would be a growth factor of 8.9 and result in 493 billion cells wherr the batch needs 427 according to mr malty.


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## DJ_L3ThAL (28/10/14)

Sorry you said 25L, the above example would still be plenty of yeast growth.


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## Dan Pratt (28/10/14)

Good thread with good info - I hadnt made a lager since batch # 39 and for batch # 90 it was time to try.....

The Lager that I made was a 1.048OG and I made a 1.5lt starter and when that finished, decanted off and added another 1.5lt's to ferment out, how much yeast that was exactly Im not sure. Both were on the stir plate at ~ 18c and when the second step was fermented out I cooled that yeast down to 5c while the Lager wort I made was cooling. I added 90seconds of pure oxygen to the wort, decented starter and pitched the yeast cold and allowed the fridge fans to bring that to 10.5c for fermentation.

I was extremely surprised at how well fermentation went, considering the wort had krausen forming after 15hrs and at day 5 was at 1.015 gravity that was much faster than I had anticipated, I was expecting a 8-10day primary ferment. I turned up the STC heat to 17c for 3days, checked gravity and is at 1.004 and today will commence a slow decrease in temp ~ 3 degrees per day till it gets to 4c and rack for lagering.

Learning/listening to MHB over the years taught me alot so I aimed for certain things like over pitching (in this case it was likely to have still been low), pitching cold and making sure it had plenty of O2 before pitching. The results will not be known until xmas as it will be lagered for 6weeks but I think its on the right track.


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## rude (28/10/14)

DJ_L3ThAL said:


> You cant do a 1.5L, remove the top layer and add another 1.5L to the freshly grown yeast population. Youll get minimal growth. Each step needs to INCREASE in size.
> 
> E.g. 10mL yeast into 100mL wort. Then resultant yeast into 1L etc. Each step needs to have the balance between amount of yeast and volume of wort known as the inoculation rate to maximise the amount of growth you get whilst not stressing out the yeast.
> 
> A good rule of thumb example would be one reasonably fresh white labs vial (50% viable) straight into a 3L starter (on a stir plate) wort for a 23L batch at 1.050. This would be a growth factor of 8.9 and result in 493 billion cells wherr the batch needs 427 according to mr malty.


According to mr malty at 50% 21st of the 8th month viability you would need 2 vials and a 3.8 litre starter
So inoculation rate is 10x MHB uses 6x but said 10x is the step up rate
What is the first step up from a wyeast smack pack in date ?
Been up all night, shift work had better sleep on this food for thought
Thanks DJ will come back to this might have to go to the yeast section & do some reading


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## DJ_L3ThAL (28/10/14)

Sorry mate your first sentence is confusing me (I'm at work so I'm not surprised)...

Both white labs and wyeast packs are both 100 billion cells at the time of manufacture, every day after this they decrease at a predetermined rate chosen by mr malty. They each have different best before dates (WL being after 4 months and Wyeast after 6 months). Just take 4 months as its conservative.

So 50% viability is assuming your packet is 2 months old. Every time you brew you'll need to ascertain your viability if you want good metrics to work off. I was merely guessing you have 50% viability, check your pack and redo the calculation in mr malty accordingly and you will be on the right track.


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## MHB (28/10/14)

[SIZE=medium]Couple of catch-up replies[/SIZE]

[SIZE=medium]Yes the wort needs to be aerated, there really is no difference between a starter and a wort, we want exactly the same things to happen in the wort as happen in the starter. Aerating to 10 ppm with O2 and having a healthy wort means that not only does the yeast reproduce but it consumes a bunch of stuff in the wort (proteins, lipids and other fatty acids...) that we want removed (they contribute to staling of the beer and can decrease head) and that the yeast regard as vital nutrients.[/SIZE]
[SIZE=medium]Turns out that at around 10ppm of O2 the yeast will run out of everything at about the same time, before switching over to anaerobic fermentation - result is maximum population of healthy yeast, and minimum amounts of undesirable wort constituents, big win all round.[/SIZE]

[SIZE=medium]Stir Plates? Well I suspect you would be much better off investing in O2, yes stirring helps but I think there is no way you are going to get enough O2 into solution on a stir plate to achieve anything like the assumed rates of reproduction. Likewise with the wort proper, you simply can’t get enough O2 into solution by pouring, splashing, shaking, whisking or even talking harshly. Oxygen or a HEPA filtered air supply really are the best (for me only) choices.[/SIZE]

[SIZE=medium]Putting a fan in the fridge; Well it dramatically improves the rate of cooling of the wort, think about wind chill factor, you feel colder on a windy day than you do on a still day at the same temperature, moving air removes heat faster. Secondly, a fridge can easily be 5oC different between the top and the bottom, where are you measuring the temperature.[/SIZE]
[SIZE=medium]I have seen ferments stall because the yeast at the bottom is so cold it goes dormant (or at least gets very sluggish) while the top is reading 17oC, if the bottom layer is 12oc some ales aren’t going to be too happy.[/SIZE]

[SIZE=medium]Racking/Trub drops; in the Temp/time profile from Kunze, you will see four drops, at least one of them is because they are cropping the yeast for immediate repitching. By choosing the yeast collected between drop 2-3 they have selected for yeast that will keep working right to the end, 0-1 will remove any trub and dead yeast, 1-2 yeast that hasn’t kept working until the beer is fully attenuated, 2-3 the best yeast for repitching and before too much haze trub has had time to sediment.[/SIZE]
[SIZE=medium]As home brewers how often we need to rack/drop will depend on what we want to do with the yeast. If we are cropping to repitch then the process in Kunze would be ideal, if the yeast is going to waste then we could get away with two drops (one being just before packaging) and one at or near terminal gravity.[/SIZE]

[SIZE=medium]Diacetyl rest and warming up; If you pitch enough yeast these won’t be necessary, again referring to Kunze, a Diacetyl rest is a remedial measure to fix a problem caused by under pitching, if you don’t have a Diacetyl problem it isn’t necessary. Similarly with ramping up the temperature at the end, again if the wort has attenuated fully it isn’t necessary.[/SIZE]
[SIZE=medium]Having said all that, it is well worth doing a force test (a small portion of the wort fermented warm, will attenuate the same but do it a lot faster) so you know what the FG is going to be. As we probably won’t be pitching anything like commercial quantities of yeast, it’s a good idea to check for both complete attenuation and the absence of Diacetyl. Which links back to the fan part above, a fan is a heater, it will heat the wort and the fridge just by running, my last fridge had 2 big fans and would reach 40oC if the fridge wasn’t turned on, more than enough heating for a ramp up or Diacetyl rest.[/SIZE]

[SIZE=medium]Lager brewing is one thing guaranteed to bring out my inner nerd. It is a very technical process, quite challenging and for me anyway a lot of fun, it does require preparation and planning.[/SIZE]
[SIZE=medium]If you want to make lager I think it’s best to plan a series of them, start with the lightest one and use your ever growing yeast slab to brew bigger and bigger lagers until you have enough yeast to make a hell big Baltic Porter[/SIZE]

[SIZE=medium]Cheers excuse the ramblings but I do like lager brewing.[/SIZE]
[SIZE=medium]Mark[/SIZE]


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## TheWiggman (28/10/14)

Many cheers.

Whilst I haven't made rubbish beers so far I do have some differences between other posters. My lagers have taken about 3 weeks to reach FG (though the last few points take a long time at low temps) but I'm 80% there in 2 weeks including a diacetyl rest. Those who get to FG quicker typically either have larger Erlenmeyer flasks than I do or use O2. Haven't heard a single person complain about spending money on an O2 kit.

Might have to put one on the Christmas list. Lord knows I've spent enough cash on this hobby and I do love my lagers. If I could enjoy my lagers even more then money well spent I suppose. Might make my lagering temp process a little simpler too.

About time I reconsidered the way I handle my starters too and might invest in some nutrient.


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## GalBrew (28/10/14)

My lagers take around 8-10 days to hit terminal gravity. Even pitching cold at 100C and doing the bulk of the ferment at 120C (and a D-rest) the ferment takes off like a rocket when pitching well, giving nutrients, oxygenating etc.


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## technobabble66 (28/10/14)

Apologies if this is a silly question, but:
I'm assume/hoping the lagering phase can be done (entirely) in bottles. Is this correct?

I believe the beer is fully attenuated at the end of the D-rest. So all fermentables should be consumed and CO2 production is finished. Hence I'm hoping it's safe to put into primed bottles. 

However, I know the lagering phase allows this special yeast to further clean up various trace compounds in the beer. Would this produce extra CO2?
Do any of the other byproducts of the lagering phase need to be volatized off and hence you should not store the lagering beer in a sealed container?
Does the addition of priming dextrose/sucrose detrimentally affect the lagering phase?

Apologies for being a bit OT, but I'm hoping it's ok as it's relevant to the whole lagering phase thing. :lol:


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## MHB (28/10/14)

Ideally not done in bottles - sorry
The old name chill proofing tells a story. Lagering gives the haze time to form and precipitate, rack cold then prime. A lot of brewers prime with an ale yeast (I think 514 and S-33 are about the best, but am liking the newish Cask and Bottle from Danstar CBC-1). If you don't rack at the end of lagering the haze will go back into solution - undoing most of the benefits of lagering.
You are very likely to end up with hazy lager
Mark


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## technobabble66 (28/10/14)

Thanks MHB. 
That makes sense. 

Bugger!!


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## manticle (28/10/14)

If you consider the products that get dropped out by lagering, you ideally want to be able to leave them behind rather than take them with you to the bottles.


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## squirt in the turns (28/10/14)

Coming back to the oxygenation question: right now I'm fermenting 40 litres of pilsner that I no-chilled in 2 corneys. Each got a 5 L starter of WY2042. I pressurised each keg with O2 (the cylinder and regulator kit MHB sells), via the liquid post (no air stone), and shook them about, with the pressure at regulator maximum (no idea what this was as the reg does not have a low-side gauge). Interestingly, unlike with CO2, shaking the keg under O2 pressure did not seem to encourage any more gas to dissolve - it bubbled in while I was dialling the pressure up but that was it.

One keg I then emptied into a fermenter via a line connected to the liquid out post, using CO2 to push it once the O2 pressure was not enough - possibly counter-productive as would have led to CO2 absorption? The other keg I left pressurised with O2 for about 8 hours (pitched yeast before adding O2), and it is still fermenting in the keg, with the pressure release valve open. I'm intending to get a spunding valve to try pressurised fermentation, so the wort will be under O2 pressure even longer (until the CO2 from fermentation brings the pressure above whatever the valve is set for).

It will be interesting to see if there is any noticeable difference between the beers produced by these methods.



MHB said:


> Stir Plates? Well I suspect you would be much better off investing in O2, yes stirring helps but I think there is no way you are going to get enough O2 into solution on a stir plate to achieve anything like the assumed rates of reproduction. Likewise with the wort proper, you simply can’t get enough O2 into solution by pouring, splashing, shaking, whisking or even talking harshly. Oxygen or a HEPA filtered air supply really are the best (for me only) choices.


Interesting that you say that, Mark. For a starter, would you oxygenate when first made, then put it on stir plate? Or continuously oxygenate (impractical and too expensive, surely)? It occurred to me when I was transferring the pilsner I mentioned above that some of the O2 I got into the wort under pressure would be coming out of solution during the transfer and therefore be wasted. I would have thought that the same thing would happen to a starter hit with O2 at the beginning then put on a stir plate - the agitation would cause the O2 to come out of solution before the yeast had a chance to utilise it.


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## manticle (28/10/14)

Unless I'm much mistaken, the main (sole) point of a stir plate is to continually oxygenate wort to maximise cell growth. If you have access to pure oxygen, surely you can bypass the stirplate altogether?


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## squirt in the turns (28/10/14)

manticle said:


> Unless I'm much mistaken, the main (sole) point of a stir plate is to continually oxygenate wort to maximise cell growth. If you have access to pure oxygen, surely you can bypass the stirplate altogether?


Well, it also keeps the yeasties in suspension. This seems like it would make sure that they always have access to fresh sugarz, instead of floccing out and sleeping? Maybe this makes no difference, in which case the best approach is to oxygenate it at the start, then leave it be. The other touted advantage of the stir plate is that it drives off CO2, so if you went to the trouble of oxygenating the starter, then put it on a stir plate, would it similarly drive off dissolved oxygen? This is what I was getting at in my post above, where I describe the process of oxygenating under pressure, but then possibly negating the benefits by agitating the wort.

I read the answer to the question "Should I add oxygen to my starter?" in this Mr Malty article as tentatively stating that a stir plate is the best option, even if pure O2 is available.


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## MHB (28/10/14)

CO2 is much more soluble than is O2 but each gas basically ignores the other, the CO2 wont reduce the amount of O2 and I doubt it will make much difference.
I have left continuous aeration alone, its a sight more complicated and as mentioned can be more expensive to set up, but its not all that dear if you shop smart. The biggest problem is that at too high a concentration Oxygen becomes toxic so you want to know what your doing or you can poison the yeast.

A stir plate stops the yeast lying on the bottom surrounded by other yeast rather than a nice food supply (wort), what I have been discussing is getting your 10ppm of O2 into the wort, getting the yeast in there and letting it brew out, one full lifecycle. Using a stir plate will help this happen a bit faster but I doubt that you will be getting much more Oxygen into the wort unless the flask is open and then there is a very high risk of infection.

If you were setting up a continuous aeration system, I would consider using air rather than Oxygen as you cant get to toxic levels with air, there are foaming issues so a good anti-foam agent might be useful, if using Oxygen you would need a timed on/off solenoid valve and some way to control it, again an anti-foam agent.

I have a couple of yeast propagator flasks (bioreactors) they have stirrers and O2 input, have to get them set up some time - will make getting huge populations easier.
Mark


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## Black n Tan (28/10/14)

manticle said:


> Unless I'm much mistaken, the main (sole) point of a stir plate is to continually oxygenate wort to maximise cell growth. If you have access to pure oxygen, surely you can bypass the stirplate altogether?


A stir plate also allows CO2 to dissipate and CO2 inhibits yeast growth

EDIT: Jamil on MrMalty states the following "You'll get far healthier yeast and far more yeast growth if the yeast have oxygen throughout the process. Adding oxygen at the beginning helps, but the most effective starters provide a continuous source of oxygen...There are several ways to add oxygen: intermittent shaking, a stir plate, pure oxygen, or an air pump with a sterile filter. A stir plate is perhaps the most effective method...A stir plate provides good gas exchange, keeps the yeast in suspension and drives off CO2, all of which increases yeast growth (around 2 to 3 times as much yeast as a non-stirred starter). "


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## manticle (28/10/14)

All well and good but is yeast that flocs out early in a starter the best cells to be adding to the main wort?
Yeast growth is important but not the only thing you want in a starter. You want to grow as many healthy, performing cells as you can. Presumably with an oxygenation set up you can add oxygen to a starter at any point, decant oxidised beer then feed it wort to get the yeast active again before adding to the main batch.

My yeast starters are far from optimum but from what I've read and what I've tried, I find same wort active starters to perform excellently and my next process improvement will be an o2 setup. Certainly if I was reculturing or stepping up from small splits I think a stirplate would be the way to go but I long ago gave up on that and use fresh packs, top cropping or (very rarely) fresh slurry.
Anyway I'm hypothesising a bit and typing on a phone so I'm happy to be wrong. I just think stir plates are a compromise (like many things) rather than a mecca.


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## andrewl (28/10/14)

I'm sure Jamil said on one of the BN podcasts that he gives his starters a hit of O2 approximately 24 hours in.
Believes it really boosts the cell growth.


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## technobabble66 (29/10/14)

Not that i have much knowledge nor experience with starters; however, i do have some understanding of biochemistry and cell biology. So ... 
It seems like the difference between the O2 injection and stirplate options is that the former would set up the optimal start to the process and the latter would maintain the best ongoing conditions throughout the process.
I don't know enough about what constitutes the best starter result, or rather, what would therefore have the better impact of the numbers _and_ health of the yeast. However, i'd guess the O2 provides the best initial increase in numbers but might taper off in numbers by the end of the starter production, and more importantly the health of the yeast by the end of the starter may be less than ideal as everything sits around stewing in their metabolic wastes. The stir plate OTOH probably doesn't get that initial rocketing of numbers, but provides a much more consistent and stable environment, hence the yeast should be in an overall healthier state by the time they are (decanted and then) pitched, and the numbers should eventually get up to similar level as the O2 option.
This also might better prepare the yeast for pitching into a fresh wort - going from an environment with lots of food and lower wastes levels into one with lots of food and zero wastes. As opposed to the O2 starter which has initially the best conditions but by the end its full of wastes and more resembles the final state of the wort, rather than the nice fresh new one it's getting pitched into.
I'd wonder if that might explain why there are some respected references suggesting if you had to pick one, the stir plate is the way to go - the best overall contribution to _both_ numbers and health of yeast _at the time of pitching._

All me just hypothesising. Hopefully not totally incorrect ramblings!
2c

PS: still annoyed i can't lager in bottles. I blame Martin.


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## DJ_L3ThAL (29/10/14)

technobabble66 said:


> PS: still annoyed i can't lager in bottles. I blame Martin.


I knew he had something to do with it!!!


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## Mardoo (29/10/14)

Caution, anecdotal blather follows:

I've oxygenated starter wort and gone on to use a stirplate as normal. There is what appears to be an increase in yeast mass produced versus same yeast without O2, but I haven't measured it with precision as I lack the proper equipment. O2 - plate - drop yeast in fridge - pitch. It hits the ground running and ferments out amazingly quickly. 48 hours. 

Too quickly for me. I decided to back off on O2 in starters and only oxygenate after pitching in the full brew. I get much closer to the performance I want. I was seeing very, very little ester development from yeasts like Wyeast 1469.

As I say, this is purely anecdotal as I lack proper means of measurement, nor have I run trials with the intention of working it out. It's entirely possible that the fast ferments were due to overpitching from more growth than I expected. Once I started measuring slurry from my starters with added O2 I was definitely ending up with more yeast than when I didn't add O2.


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## Eagleburger (29/10/14)

That agrees with my anecdotal evidence. The only off flavour in my lagers has been diacetyl. I am a lacking ale in my keezer atm, bu5 my next lager will be fermented in two lots. One with no oxy an plenty of yeast, other with plenty of oxy but little yeast. I believe the oxy catalisid AAL-> diacetyl reaction or lack of is my problem.


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## Mardoo (29/10/14)

Hey Manticle, should some portion of this be split off into a Yeast Starter - Theory and Practice thread?


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## manticle (29/10/14)

Probably if people want to continue the conversation. Will re-examine tomorrow at the work pc.


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## rude (29/10/14)

I did start a yeast topic on yeast starter step up as I was getting a bit off topic plus confused too
All good now though


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## Trough Lolly (29/10/14)

MHB said:


> Drifting slightly off topic, but yeast management is integral to making good lager, so perhaps not too far OT.
> Ideally we need a lot of health yeast if we want to pitch cold, unfortunately a lot of the methods mentioned here may give you a lot of yeast but I would question its health. One of the vital ingredients in yeast propagation is Oxygen, without the right balance of O2 and other nutrients the yeast can be very stressed and can produce beer that is seriously flawed.
> 
> Make a special starter wort at about 1.040 (give or take), use the recommended amount of nutrient, and aerate to 10ppm with O2. Starters should be stepped up 10X in volume and you should see a 6-8 fold increase in the population at each step. Do the numbers, work out how many cells you need and what you think you are starting with that will tell you how many steps you need. I wouldn't assume the maximum population increase (I use 6X) as the danger of over-pitching is dwarfed by the problems caused by under-pitching .
> ...


I'm with Mark on this one...I find my best lagers result from healthy, not tired, yeast and remember, you can't assume that lager strains grow as vigorously as ale strains do. Fresh ingredients, temperature control and patience are the keys to a good lager.

Cheers,
TL


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## galactaphonic (30/10/14)

Would either of these ideas work with the aim of getting bigger yeast populations?

1) Ferment half a batch size (e.g. 11.5 litres) and, when that has finished fermenting, add the second half of the batch in with the first half(making a final total of 23 litres).

2) Ferment one full batch, after fermentation is complete, leave it out of the fridge for a few weeks while you add another batch directly onto the yeast cake. After the second batch is finished, remove it from the fridge and then put the initial batch in for 4 weeks lagering, then when that's finished put the second batch in for lagering (this would mean they would be out of the fridge for several weeks in between the fermentation and lagering periods).


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## manticle (30/10/14)

For 1, google drauflassen.


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## manticle (30/10/14)

2 sounds weird.


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## DJ_L3ThAL (30/10/14)

galactaphonic said:


> Would either of these ideas work with the aim of getting bigger yeast populations?
> 
> 1) Ferment half a batch size (e.g. 11.5 litres) and, when that has finished fermenting, add the second half of the batch in with the first half(making a final total of 23 litres).
> 
> 2) Ferment one full batch, after fermentation is complete, leave it out of the fridge for a few weeks while you add another batch directly onto the yeast cake. After the second batch is finished, remove it from the fridge and then put the initial batch in for 4 weeks lagering, then when that's finished put the second batch in for lagering (this would mean they would be out of the fridge for several weeks in between the fermentation and lagering periods).


You need the bigger yeast population BEFORE you brew, so your point 2) suggests you already have enough yeast for the first batch and whether you do another batch after it or not is not within context?


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## Eagleburger (30/10/14)

manticle said:


> For 1, google drauflassen.


Cool, it has a name.


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## balconybrewer (7/4/15)

Quick question. How can you calculate ppm of dissolved O2 when the volume varies.

All of the above talks about 1-2l/m for a 23l batch, but obviously this changes if you were trying to oxygenate a small
Starter of double batch.

Cheers


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## Black n Tan (7/4/15)

balconybrewer said:


> Quick question. How can you calculate ppm of dissolved O2 when the volume varies.
> 
> All of the above talks about 1-2l/m for a 23l batch, but obviously this changes if you were trying to oxygenate a small
> Starter of double batch.
> ...


Double the batch, double the time. So for a 23L batch use 1 minute at 1l/min and for 46L batch use 2 minutes at 1L/min. I don't use oxygen for starter as a stir plate provides better results than just oxygenating at the start.


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## balconybrewer (11/4/15)

Anyone else got a calculator, chart or other method of calculating O2 ppm based on flow rate / time and volume?


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## MastersBrewery (11/4/15)

I think the above is the accepted pratice and I haven't seen any other methods widely used.


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## wobbly (11/4/15)

Interesting post by Rude.



rude said:


> Funny you should say that Galactaphonic because the other day I had a munich dunkel brewed with a wyeast lager yeast
> It was brewed with a williamswarner unit at my local LHBS it was very nice
> The bloke told me that it was drinking at 13 days ofter fermentation due to it being under pressure clear as a bell
> Ales only 7 days problem was the price of the unit
> ...


Fermenting under pressure and the processes recommended when brewing with a WilliamsWarn is/maybe a* "Paradigm Shift"* in conventional thinking about brewing and lagers.

In post #2 MHB talks about why you need large starters and time (primarily because you are fermenting colder to prevent unwanted esters etc) also that you need time (many weeks) to get the yeast and cold break to settle out
Fermenting under pressure limits (even prevents) the formation of esters and other off flavours when fermented at higher temperatures (15/18C for lagers and 23C for Ales) and the higher temperature means fermentation is over and done with in about 4 to 6 days 

In the WilliamsWarn yeast and cold break still in suspension after only 12 hours cold crash are removed by the use of two doses (1st 30mls and 2nd 20mls) over 48 hours of Colloidal Silica Oxide. I accept that this doesn't meet the German purity laws.

A WilliamsWarn isn't/doesn't tick most/any boxes for most on this site but as stated by "Rude" above it can and does result in a very nice beer

Cheers

Wobbly


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## MastersBrewery (11/4/15)

Wobbly,
I have to disagree, the WW ticks alot of boxes.
The price box is the biggest of all, this is the box it missed.

MB


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## MHB (11/4/15)

Pressure fermentation has been getting quite a few mentions of late - enough to make me go and read up on it - not enough there to interest me in doing it.
It isn't a magic bullet, it can have some advantages but there are potential drawbacks to. The idea was developed to reduce Diacetyl in lager brewing and get faster maturation. The pressure isn't applied until 50% of the fermentation is complete, the temperature is allowed to rise to around 20C and the applied pressure is much less than some home brewers talk about using, very large (commercial) yeast pitches are required - if you get it wrong there is a big chance if dramatically increasing the amount of Acetaldehyde, getting incomplete attenuation and other metabolic side issues all of which you don't want. The target pressure is enough to give 5.5g/L of dissolved CO2 at lagering temperature (~1oC) so we are talking roughly 80kPa.

I think pressure fermentation would be best left to the big brewers with high-end temperature, pressure, rate of rise monitoring and a burning desire to knock 7 day out of a 28 day brewing cycle, me I would rather be patient.
Mark


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## wobbly (11/4/15)

The comment that pressure isn't applied until 50% of fermentation is completed isn't consistent with the WilliamsWarn process.

When fermenting a Lager (or Ale) the pressure is allowed to progressively increase from the very start of the ferment up to what ever pressure setting is set on the Variable Pressure Relief Valve.

Using one packet of W34/70 in 25lt of 1.055 wort at an initial temperature of 15C (for the first 3 days followed by a further 3 days at 18C) the pressure will build to the VPRV setting which in my case is generally around 1.5bar (21psi) in about 36 hours which is only about 25% of the total ferment time of 6 days

Also MHB infers that around 80kPa (11psi) is the norm for lagering conditions where as the WW process towards the end of the ferment is about twice this value at around 1.5bar (22psi/160kPa)

As far as the need to use "very large (commercial) yeast pitches" this is not the requirement in the WW with wort below 1.060 where I X 11.5g packet is all that is required. For worts above 1.060 then 2 X 11.5g packets is recommended 

This post isn't about challenging what MHB has posted, rather highlighting that pressure fermenting in a WW is a* "Paradigm Shift"* in traditional Home Brewing - albeit at quite a significant $ investment

Cheers

Wobbly


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## MHB (11/4/15)

I could easily think you were challenging what I posted, except that in a couple of respects we are talking at cross purposes.
I am sighting the research that has been done on pressure fermentation to reduce Diacetyl and accelerate maturation (read Kunze and a couple of other references) whether or not a manufacture of a piece of brewing equipment has applied that research to best effect is another question entirely, it does not however negate what the research indicates is best practice.

The 80kPa referred to is as part of the maturation process, it is obviously too low to be the carbonation pressure for a Lager, which would be the endpoint pressure in the WW.
The WW is an novel piece of kit with many interesting applications of what is quite old/common commercial brewing process to home brewing, If I had the spare $'s I would be happy to own one, but be aware that it is far from being a Paradigm Shift (nice marketing but not really true) and that the designer has (for economic reasons I suspect) made some compromises and that there may be a better ways to apply the knowledge we have.

Just remember that a good blurb isn't research
Mark


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## wobbly (11/4/15)

With all due respect I contend that the WW Process is a "Paradigm Shift" in the Home Brewing situation from plastic fermenters to an all in one stainless steel vessel accommodating every facet of fermentation from wort /yeast pitching to consuming chilled, carbonated crystal clear beer from the same devise all within 7 to 9 days depending on style (Ale or Lager)

I have spent many an hour on Google and there is nothing else either available on the market or DIY that does all of this (albeit at a price) in a single vessel

Guys have been pressure fermenting in cornys for quite a while but they still have to deal with yeast settlement and cold break removal somehow then carbonate and chill it before it is ready to consume.

From what I have read and seen on this site MHB is held in high regard and very knowledgeable and I don't question that and neither is it my intention to trade blows with him on the question of lagering and time required using traditional home brew equipment such as plastic or stainless steel fermenters/conicals.

I mearly entered the discussion to put a view that there is a system/setup on the market (again albeit at a high cost compare to other equipment generally used in the home brew scheme of things) that doesn't require lagers (Pilsners) to have quite long (weeks) of cold lagering before they are drinkable

And with that said I will now move on

Cheers

Wobbly


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## Yob (11/4/15)

Another infomercial brought to you by....


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## luggy (11/4/15)

Hardly a paradigm shift when 90% of brewers can't afford it


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## MastersBrewery (11/4/15)

luggy said:


> Hardly a paradigm shift when 90% of brewers can't afford it


 98%


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## DJ_L3ThAL (11/4/15)

99.9%, the extra 1.9% are the super tight ass ones!!! ;-)


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## Goose (11/4/15)

You don't necessarily need a WW to try fermentation under pressure. Maybe you do need a WW if you want to dispense beer from your fementer once its complete.

The WW is a single vessel fermenter and dispenser all in one. But damn, You can only serve beer after the ferment is complete.

What do you do while your are fementing when you want a cold one ? Drought between batches ?


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## Yob (11/4/15)

We all know where this is headed... Again


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## balconybrewer (11/4/15)

This question got lost in the ww debate, can anyone help me out with this?

Anyone else got a calculator, chart or other method of calculating O2 ppm based on flow rate / time and volume?

I.e how long do I oxygenate a 4lts starter for or a 50lt wort at a specific flow rate (2lts / minute)


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## Yob (11/4/15)

I don't know off the top of my head mate, I know it's been discussed in detail in other threads though.


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## MastersBrewery (11/4/15)

Comonly espoused 1m/1lpm for 23L for your 12ppm of O2 the advice beyond that, is to double the time for 46L, so in other words it scales. so for your 4L 10-12 second would be in the ball park. Myself as others have said I believe the stir plate does a good enough job of oxygenating the starter I usually have it spinning for 15m before pitch. Up to you, how you proceed but be sure to lets us know what method you went with and results. The wort I'd hit for 2min as per above.
good luck.


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## DJ_L3ThAL (12/4/15)

The method of injection will affect how the O2 bubbles are dispersed, there is no simple one size fits all answer so I would go with the commonly used parameters MB posted above.

At work we do a few aquaculture O2 injection tanks, I'll ask our market specialist if there is a calculator, but again I think it will hugely depend on your O2 outlet size. We have different systems which are all of different efficiencies based on how the diffuser, be it nozzles or a simple hose with holes along it's length are setup.


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## Lemon (12/4/15)

Not having read all the way back though this thread, again, I cannot recall accurately if anyone has referenced the definitive lager brewing text by Wolfgang Kunze. In tHis text he details the scientifically derived temperature vs time data and charts for lagering time.
I know that this is the data MHB refers to. His method du jour is to not to argue the point for himself but to open his copy of Kunze and invite you to read the appropriate section, then decide for yourself.

I offer the same opportunity.

Lemon


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## manticle (12/4/15)

Whose kunze text are you offering the forum to open?


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## Lemon (13/4/15)

Good point, I haven't the 149 Euro for my own.
I believe that braukiser , reproduces most of this info from Kunze. From my recollection, the lagering temp and time is distilled down to -1C for 4 weeks, for every degree C above that add another week.

Lemon


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## booargy (13/4/15)

It is well worth the coin


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## manticle (13/4/15)

Yes it's on my list.


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