[S. cerevisiae]

Is that not the point of a yeast calculator?

You can't blindly input numbers and expect every beer to come out perfect.  But for determining your pitching rate, it's a good starting point before you start adjusting the other variables (oxygenation, increasing/decreasing pitching rate, etc).  And when I've done cell counts, they haven't been so far off that it makes using it as a guide worthless.

If there is one thing on which Kai Troester, Steven Deeds, and I agree, it's that real world numbers do not always correlate with the numbers produced by yeast calculators.  For example, how does a yeast calculator know that a culture is 59% viable after 2 months.  I have cultures that will remain viable for up to two years on slant.  I have other cultures that I have to subculture within six months or risk losing the culture.  The only thing that will teach a brewer how to pitch correctly is experience with a particular yeast culture. 

Yeast cultures are a little like atomic bombs in that one does not have to get all that close to the optimum calculated pitch rate in order for the culture to do its job correctly.  The difference between 200 billion cells and 300 billion cells is insignificant when making a starter because yeast cells grow exponentially at a rate of initial_cell_count x 2ⁿ, where n equals the time in minutes since exiting the lag phase divided by 90.  The difference between 200 billion cells and 400 billion cells is 200 x 2¹, which is 90 minutes of propagation time. 

Given two cultures of the same strain that are not drastically different in cell count (i.e., not several multiples), the limiting factors are always going to be dissolved oxygen, available carbon and nutrients, and initial yeast health.  A 1L starter that is pitched at the end of the deceleration phase will almost always perform as well if not slightly better than a 2L starter of the same strain that is allowed to ferment out.

[a10t2]

Yeast cultures are a little like atomic bombs in that one does not have to get all that close to the optimum calculated pitch rate in order for the culture to do its job correctly.

Having built both, I'm not sure how I feel about this analogy.

[S. cerevisiae]

Asking people to stop using yeast calculators is a bit bold. While you may have the skill, equipment, and knowledge required, many of us do not. Sure yeast calculators generalize and make assumptions, but it is the best many of us can do. I for one have zero interest in buying a microscope, counting slides, dyes, and all the other equipment when a bit of software will get me close enough.

Learning how any given culture behaves does not require one to own any lab equipment.  You would be surprised to discover how much can be learned about any given yeast culture using little more than one's senses, a writing implement, and paper (I have kept a paper log since I started brewing in the early nineties).  Scientists have been working this way for thousands of years.  For example, Dr. John Snow proved that cholera was a waterborne disease using a writing implement and paper.   He did so by tracking the number of deaths at each address in London's Soho District during a major cholera outbreak.  Dr. Show noticed that the only address on Broad Street where there were no cholera deaths was the Lion Brewery (Huggins and Company, Ltd).  While the Lion Brewery shared the same water supply as the affected area, the people who worked at the brewery did not contract cholera because they drank beer instead of water and the brewing process kills the microbe that causes the disease.  What's even more surprising is that Dr. Snow made this discovery before Louis Pasteur founded the field of microbiology.

[narvin]

If there is one thing on which Kai Troester, Steven Deeds, and I agree, it's that real world numbers do not always correlate with the numbers produced by yeast calculators.  For example, how does a yeast calculator know that a culture is 59% viable after 2 months.  I have cultures that will remain viable for up to two years on slant.  I have other cultures that I have to subculture within six months or risk losing the culture.  The only thing that will teach a brewer how to pitch correctly is experience with a particular yeast culture. 

Yeast cultures are a little like atomic bombs in that one does not have to get all that close to the optimum calculated pitch rate in order for the culture to do its job correctly.  The difference between 200 billion cells and 300 billion cells is insignificant when making a starter because yeast cells grow exponentially at a rate of initial_cell_count x 2ⁿ, where n equals the time in minutes since exiting the lag phase divided by 90.  The difference between 200 billion cells and 400 billion cells is 200 x 2¹, which is 90 minutes of propagation time. 

Given two cultures of the same strain that are not drastically different in cell count (i.e., not several multiples), the limiting factors are always going to be dissolved oxygen, available carbon and nutrients, and initial yeast health.  A 1L starter that is pitched at the end of the deceleration phase will almost always perform as well if not slightly better than a 2L starter of the same strain that is allowed to ferment out.

Sure, the viability calculator is bunk.  The Wyeast one doesn't even have that feature. If you're buying new yeast to make a starter, the calc will give you 90%+ anyways.  For fresh yeast, viability isn't as important since a continuously aerated starter is where you're most likely to get the maximum yeast growth per liter of wort (i.e. an atomic bomb). 

Yeast cell growth in standard brewing conditions, with one initial aeration, is considerably less.  Even one fewer phase of reproduction can make a big difference in the final amount of yeast.  It will "do the job", but will you get the ester profile you want or the attenuation?

There's no problem with pitching less if you're doing it on purpose, but I wouldn't suggest that people new to the hobby pitch less than 0.75 mil/ml/Plato.  And at the homebrew level, you're almost always overestimating (at least, that's what I've found from doing cell counts). 

I would suggest using a yeast calculator because a repeatable process is the first step to learning what works.  Then you can adjust your SWAG from there.  It's better than dropping the bomb on your beer and hoping for the best.

[erockrph]

I would suggest using a yeast calculator because a repeatable process is the first step to learning what works.  Then you can adjust your SWAG from there.  It's better than dropping the bomb on your beer and hoping for the best.

Bingo. It's very much like using an IBU calculator. You're not likely to hit the measured number. You're probably not even particularly close. But you need some sort of benchmark for measuring your initial conditions, and some way to quantify what changes you make for subsequent batches. The calculator doesn't need to give you a number that equates to anything in the real world. It just needs to model conditions close enough where you can compare and adjust between batches.

And at that point the pencil and paper become the more important tools. In the end, we brew for ourselves and our own palates. A number like 55IBU or 250 billion cells means nothing until you can quantify the results with your own palate.

[klickitat jim]

Im learning to like this guy more each day. I quit using a calculator after doing several repitches. It became apparent to me that at my level ballparking my pitch was just as good as a calculated guess. My routine now is 3/4 cup of liquid (meaning not solid) repitch for ales, a full cup for lagers or huge ales, or a fresh smack pack in 2L stir starter for ale, and two packs in two 1.5L starters for lager. And all of that is fudged here and there depending on gravity or desired ester profile.

[HoosierBrew]

I would suggest using a yeast calculator because a repeatable process is the first step to learning what works.  Then you can adjust your SWAG from there.  It's better than dropping the bomb on your beer and hoping for the best.

Bingo. It's very much like using an IBU calculator. You're not likely to hit the measured number. You're probably not even particularly close. But you need some sort of benchmark for measuring your initial conditions, and some way to quantify what changes you make for subsequent batches. The calculator doesn't need to give you a number that equates to anything in the real world. It just needs to model conditions close enough where you can compare and adjust between batches.

And at that point the pencil and paper become the more important tools. In the end, we brew for ourselves and our own palates. A number like 55IBU or 250 billion cells means nothing until you can quantify the results with your own palate.

+2.  Brewers, especially new ones, need something to get them in the ballpark,ie., a basis to pitch enough yeast to make a good beer. I agree that experience with a particular strain really helps in assessing any future changes needed, just as experience with a particular malt, hop or water profile, for that matter. Of course viability numbers are undoubtedly 'ballpark' at best, but the calculators have helped a lot of brewers pitch roughly enough yeast to meet their goals.

[69franx]

Quote HoosierBrew: +2.  Brewers, especially new ones, need something to get them in the ballpark,ie., a basis to pitch enough yeast to make a good beer. I agree that experience with a particular strain really helps in assessing any future changes needed, just as experience with a particular malt, hop or water profile, for that matter. Of course viability numbers are undoubtedly 'ballpark' at best, but the calculators have helped a lot of brewers pitch roughly enough yeast to meet their goals.

Exactly. I have made about 15 batches of ales and only 1 lager. Almost all of the ales were made with WLP001 or S05. The Märzen I made used WLP820. My questions here were in regard to WLP833 which I have never used, so the calculator helps me get in the ballpark, and maybe by the fourth or fifth time I use it, I will know where to be starter wise. My main questions were about volumes and gravities, and I think those have been handled previously in this thread. Thanks for all who helped out, even though I kind of high jacked the thread for my specific needs

[S. cerevisiae]

It's very much like using an IBU calculator. You're not likely to hit the measured number. You're probably not even particularly close. But you need some sort of benchmark for measuring your initial conditions, and some way to quantify what changes you make for subsequent batches. The calculator doesn't need to give you a number that equates to anything in the real world. It just needs to model conditions close enough where you can compare and adjust between batches.

One does not need an IBU calculator either.  All one needs is a unit of measure because we have no idea if the alpha acid rating on the package accurately reflects that current state of the hops.  Amateur brewers used HBUs/AAUs long before IBU approximations became the rage. An HBU/AAU-based hopping rate combined with a boil length is no less valid than a calculated IBU value when it comes to repeatability, and hopping schedules based on HBUs/AAUs can be calculated in one's head.

The same thing can be said about extraction efficiency calculations. Efficiency calculations only reflect reality to point where the dry basis, fine grind (DBFG) or hot water extract (HWE) values used in the calculations reflect reality.  These values can change from malting to malting and season to season.   Once again, there is a simpler unit of measure available for the job.  It's known as points per pound per gallon (or points per kilogram per liter for those who use the metric system), and its directly usable without having to enter numbers into brewing software. If a brewer knows that his/her average extraction rate is 30 points per pound per gallon (the extract from one pound of grain in a one gallon solution has a specific gravity of 1.030), all he/she needs to do to obtain the weight of the grist is to calculate the total number of gravity points in the target batch and divide by his/her PPG value.

Example:

Sierra Nevada Pale Ale has an original gravity (O.G.) of approximately 1.053.  Our average extraction rate is 29 points per pound.  How many pounds of grain do we need to make six end of boil gallons of wort in our brew house using points per pound?

Step 1.) convert the O.G. to gravity points

1.053 = 53 gravity points

Step 2.) Calculate the total number of gravity point required in the end of boil volume

6 x 53 = 318

Step 3.) Calculate the grist weight

318 / 29 = 11 pounds (rounded)

From here, it is merely a matter of breaking the grist down into percentages. SNPA is American 2-row and caramel malt. I have seen caramel percentages ranging from 3% to 10% of the grist.  Let's pick 5% for our example.

11 x 0.95 = 10.45 pounds of 2-Row
11 x 0.05 = 0.55 pounds of caramel

Or if we want to simplify measuring

10.5 pounds of 2-Row
0.5 pounds of caramel

It's that easy.

[morticaixavier]

yes, it's easy to calculate this stuff in your head or on paper. but then you have to remember, or write down, what you have done in order to have repeatability. I do not trust my memory all that much and honestly if I write something down on paper I will either lose it, or not be able to read my hand writing when I find it. If however I enter into a convenient, electronic, portable, and highly organized computer program it's all right there for me to find and interpret even years later. If that program has all sorts of calculators so it goes.

I acknowledge the importance of understanding the processes and basic science involved but I don't see the problem with using a tool to help organize the information. if you are more comfortable with a tool like pencil and paper then great. I'm more comfortable with a computer as are a lot of people. Come the apocalypse I'll start using pencil and paper again. At least once the power runs out.

[narvin]

One does not need an IBU calculator either.  All one needs is a unit of measure because we have no idea if the alpha acid rating on the package accurately reflects that current state of the hops.  Amateur brewers used HBUs/AAUs long before IBU approximations became the rage. An HBU/AAU-based hopping rate combined with a boil length is no less valid than a calculated IBU value when it comes to repeatability, and hopping schedules based on HBUs/AAUs can be calculated in one's head.

It is less valid as a model of bitterness, though.  Whether or not the model is accurate given variances in hop age, batch size, and other factors is another question.  However, "why try to predict something that can never be 100% accurate" seems like a Luddite excuse to me.

http://www.realbeer.com/hops/research.html

[narvin]

The same thing can be said about extraction efficiency calculations. Efficiency calculations only reflect reality to point where the dry basis, fine grind (DBFG) or hot water extract (HWE) values used in the calculations reflect reality.  These values can change from malting to malting and season to season.   

And, country malt will give you the lot analysis for the specific bag of malt you bought.  Keep it in a sealed container and even moisture content shouldn't change much over time.

http://countrymaltgroup.com/maltlot.asp

[S. cerevisiae]

It is less valid as a model of bitterness, though.  Whether or not the model is accurate given variances in hop age, batch size, and other factors is another question.  However, "why try to predict something that can never be 100% accurate" seems like a Luddite excuse to me.

http://www.realbeer.com/hops/research.html

I can assure you that the ephitet "geek" fits me better than "luddite."    The following posting will give you insight into my formal background: https://www.homebrewersassociation.org/forum/index.php?topic=20713.msg262726#msg262726. 

Keeping the things we can control simple because the things that we cannot control are complex is something that every technical professional worth his/her salt learns early on in his/her career.   For example, I can almost always determine the relative experience level of the software engineers who built a piece of software when reviewing the source code or reverse engineering  it.  Software that is built by bright, but inexperienced software engineers is almost always an order of magnitude more complex than it needs to be to do the job. 

Complexity for complexity's sake adds no value.   The same thing can be said about calculating IBUs, pitching rates, and efficiency percentages at the scale at which most amateur brewers work.  Sure, calculating these values is a nice intellectual exercise that offers us interesting numbers, but the acid test for accepting additional complexity should always be, does a complex calculation add significant value to the process over a less complex calculation? 

[hopfenundmalz]

We had a saying in the lab "measure with a micrometer, mark it with chalk, cut with an axe". Sometime one would add "file to fit, paint to match it up".

Any simulation needs accurate input data. Validation of predictions are also needed rather than blind faith on the computed results.

[narvin]

I can assure you that the ephitet "geek" fits me better than "luddite."    The following posting will give you insight into my formal background: https://www.homebrewersassociation.org/forum/index.php?topic=20713.msg262726#msg262726. 

Keeping the things we can control simple because the things that we cannot control are complex is something that every technical professional worth his/her salt learns early on in his/her career.   For example, I can almost always determine the relative experience level of the software engineers who built a piece of software when reviewing the source code or reverse engineering  it.  Software that is built by bright, but inexperienced software engineers is almost always an order of magnitude more complex than it needs to be to do the job. 

Complexity for complexity's sake adds no value.   The same thing can be said about calculating IBUs, pitching rates, and efficiency percentages at the scale at which most amateur brewers work.  Sure, calculating these values is a nice intellectual exercise that offers us interesting numbers, but the acid test for accepting additional complexity should always be, does a complex calculation add significant value to the process over a less complex calculation?

I understand simplicity, repeatability, and the limitations of a model.  What I don't understand is what you are advocating, aside from avoiding any methods that you haven't embraced.

The yeast growth, IBU, and extract potential calculations that I've referenced are all based on solid data.  More importantly, I'd argue that they take meaningful inputs and produce usable, repeatable results for homebrewers that are more than just an arbitrary number on paper. Showing that a possible error exists is not a reason to revert to a worse model.

I won't get into credentials in a public forum, since I think that's kind of pointless.  But I will say that you come across as someone who is, above all, set in your ways.  I have a significant amount of engineering experience, and this is one of the biggest red flags we see.  You can teach people with inexperience...