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MarkyP

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Hey guys, small batch biab brewer here. Just started to use Brewfather, the UI/UX is great compared to beer Smith.

Just a quick question regarding water amount

my aim is to have 5.5 litres in kettle after boil. I brew a little bit extra to account for losses like trub. With my boil off rate of 2.4 litres in Brewfather it says I need 7.9 litres of water at the start of the brew. This all seems straight forward.

when I go to my first recipe created, an Irish red, and scroll down to the water Section It says the water amount is 8.4Litres, This looks like the .5L/kg grain absorbtion rate in my profile being added to my 7.9liters of water.

So my question is should I start off with 8.4 litres of water in my kettle? Or 7.9.

On a side note I noticed when creating an equipment profile it says pre boil and post boil volumes are hot including 4% expansion. So let’s say my pre boil volume is 8.4 litres which is measured hot in brewfather with 4% expansion. When I’m filling my kettle with cold water shud I account for the 4% expansion, should I be using 8.064 litres of cold water which when heated will be 8.4 litres.

just trying to really nail down my water amounts
 

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McKnuckle

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7.9 is the pre-boil volume, i.e. the amount of liquid remaining after grain absorption. So 8.4L is the starting volume, and would imply that your recipe comprises 1 kg of grain.

I hate the 4% expansion thing in brewing. I always turn it off or ignore it in every piece of software I've used. I greatly prefer to just normalize all volumes to room temperature. After all, your beer ends up cold! I dislike this particular aspect of Brewfather, but it's like all the others.

There is a setting in the "Mash/sparge water calculation method" section to "ignore boil expansion." You can try that. But it's mutually exclusive with "no sparge" which doesn't make sense to me. You can also use "no sparge" and play with the min/max mash and sparge volume values. You can set max sparge volume to 0, for example.

Bottom line, the math is simple and you can check it yourself. Grain absorption + boil-off + a nominal amount of kettle leftovers = total water. I would try to avoid getting obsessive about 0.0x liter accuracy if you can. 0.056 L is only 1/4 cup.
 
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MarkyP

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Thanks for the quick reply, thanks for confirming that grain absorption. The way you worded it makes perfect sense.
I think I will ignore that 4% as I don’t think it would effect the overall too much.
 

VikeMan

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I hate the 4% expansion thing in brewing. I always turn it off or ignore it in every piece of software I've used. I greatly prefer to just normalize all volumes to room temperature. After all, your beer ends up cold! I dislike this particular aspect of Brewfather, but it's like all the others.
FWIW, BrewCipher doesn't dork around with expansion.
 

jdudek

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I believe grain absorption+Boil off=total wort, not total water. The wort volume is larger than the volume of water you start with because dissolved sugars will increase the volume. I believe for 1kg of sugar it’s about 0.5L. If you’re using 1kg of grain with 80% potential, that’s 0.4L less water you need to start with.

i use brewfather as well and I believe they are doing this calculation wrong. 7.9L is not the starting water. More like 7.5. 7.9 will be the resulting wort volume.

this will have an impact of maybe 3-5 gravity points in the end. If that’s a dont care for you, you don’t need to worry about any of this. But it’s good to know if you ever wonder why you don’t quite hit the numbers the software throws out.
 

skarp0ye

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Hi,

You don't have to manually deal with the boil expansion, this is only to make it easier to compare values when you do measurements in your batch, since you don't want to cool down the liquid before noting your pre-boil or post-boil volumes.

When it tells you to use 8.4L of water this is with no expansion, and is calculated based on your grain absorption, to give you the said pre-boil volume (excluding expansion automatically). So fill your kettle with 8.4L cold water.

Please share the recipe share link if you have any follow up questions (share button).

Best regards Thomas (Brewfather developer)


Also this is a good reference: Setting up your equipment profile
 

jdudek

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@skarp0ye, thanks for brewfather. I’m a paying user and I love it.

I wonder if you could comment on this thread, specifically the conclusion, where it appears that pre boil gravity calculations are off.

as a quick example I put in 5kg of 80% yield grain into brewfather. I’ve also put in 4% grain moisture in the malt details. With my equipment profile, the software comes up with strike water 28.83 L and a pre boil gravity of 1.051/12.6P

plugging the same numbers into the Braukaiser formula and assuming 4% grain moisture generates a gravity of
1.047/11.8P. 4 points less for 100% conversion.

the difference seems to be in wort vs water. Your suggested water volume seems to be the wort volume. Those are not equal since dissolved sugar contribute to volume at something like 0.5L/kg.

if I plug 28.83-(5*0.5) in the braukaiser formula I get 12.7P, basically the same as brewfather.

would like to know your thoughts here and please correct me if I’ve gotten anything wrong (highly likely!)
 

McKnuckle

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@skarp0ye I pay for and enjoy Brewfather. Thank you for the excellent software! I appreciate the opportunity to interact with you here.

[Edit - my post is related to the efficiency post above, please read on...]

The water calculation algorithm is very confusing. I have literally spent hours with it and a spreadsheet, trying to reverse engineer the calculations.

What I have found is that if you select "Ignore Boil Expansion" or "No Sparge" for the mash/sparge water calculation method, the app expresses the total volume of water needed as hot. That is, it is 4% more than you actually need. This is not how most brewers work. We measure out our starting volumes with cold or room temp water.

If you select "Default," then the needed water volume drops back to the normal room temp amount. But this is not intuitive, because whether one sparges or not has no bearing on the way we measure water. I don't think most brewers are measuring their sparge water by kettle height when it is hot. They measure it at the beginning to fill an HLT or set it aside.

If one measures out cold water with the first two settings, the OG will always be slightly less than expected, because you're using too much water. You have to drop the mash efficiency setting below what it should be in order to have Brewfather compensate for this with more grain, so another artifact of the problem is that the mash efficiency calculation is not accurate (see above post).

You are also treating the user's entered value for evaporation as hot. This means that when water volumes are normalized post-boil, the net effect is that less boil-off volume was accounted for by the software. Brewers expect the boil-off rate to be normalized, so this is another source of inaccuracy.

I can provide examples of all this, but I don't want to overwhelm the thread.

I strongly feel there should be a global setting in the equipment setup that completely removes the 4% expansion/contraction factor. Just allow us to get rid of it entirely and treat all water as room temperature if we wish.

Respectfully...
 

skarp0ye

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@skarp0ye I pay for and enjoy Brewfather. Thank you for the excellent software! I appreciate the opportunity to interact with you here.

[Edit - my post is related to the efficiency post above, please read on...]

The water calculation algorithm is very confusing. I have literally spent hours with it and a spreadsheet, trying to reverse engineer the calculations.

What I have found is that if you select "Ignore Boil Expansion" or "No Sparge" for the mash/sparge water calculation method, the app expresses the total volume of water needed as hot. That is, it is 4% more than you actually need. This is not how most brewers work. We measure out our starting volumes with cold or room temp water.

If you select "Default," then the needed water volume drops back to the normal room temp amount. But this is not intuitive, because whether one sparges or not has no bearing on the way we measure water. I don't think most brewers are measuring their sparge water by kettle height when it is hot. They measure it at the beginning to fill an HLT or set it aside.

If one measures out cold water with the first two settings, the OG will always be slightly less than expected, because you're using too much water. You have to drop the mash efficiency setting below what it should be in order to have Brewfather compensate for this with more grain, so another artifact of the problem is that the mash efficiency calculation is not accurate (see above post).

You are also treating the user's entered value for evaporation as hot. This means that when water volumes are normalized post-boil, the net effect is that less boil-off volume was accounted for by the software. Brewers expect the boil-off rate to be normalized, so this is another source of inaccuracy.

I can provide examples of all this, but I don't want to overwhelm the thread.

I strongly feel there should be a global setting in the equipment setup that completely removes the 4% expansion/contraction factor. Just allow us to get rid of it entirely and treat all water as room temperature if we wish.

Respectfully...
Thanks. Will look into your feedback.

You are right the "No Sparge" is using hot pre-boil volume by mistake, will have this corrected in the next patch. Will also add a field to set the expansion manually.

The "Ignore boil expansions" calculates with this error by design, to have the Brewfather calculation match up when exporting to a certain other system that many users use.
 

McKnuckle

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Great stuff. I think we'll find that the mash efficiency outcome changes too, because right now, the pre-boil and original gravity values are the same regardless of the mash/sparge calculation. And this can't be, because "Default" starts with less water than the other two. So given the same amount of grain and same mash eff. percentage, "Default" would produce a higher OG than the other two settings.

Thank you so much for checking into this!
 

McKnuckle

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@jdudek, I am using doug293cz's "Mash and Lauter Simulator" spreadsheet, which he in part derived from Braukaiser's work.

I am finally able to make Brewfather match the outputs on this sheet! BF is definitely not accounting for a 4% grain moisture content by weight. When I set that variable to zero on the spreadsheet, I can get both pre-boil and original gravities to match up when the same mash efficiency is entered in both tools.

When I set the variable to 4%, the gravities in BF are then 2-3 points higher than on the spreadsheet. This means that if you are basing your BF efficiency on what you've learned from other tools, you will undershoot the OG estimated by BF by a couple of points.

You mention "I’ve also put in 4% grain moisture in the malt details" - and yet I can't find this option. Can you advise?
 

jdudek

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@jdudek, I am using doug293cz's "Mash and Lauter Simulator" spreadsheet, which he in part derived from Braukaiser's work.

I am finally able to make Brewfather match the outputs on this sheet! BF is definitely not accounting for a 4% grain moisture content by weight. When I set that variable to zero on the spreadsheet, I can get both pre-boil and original gravities to match up when the same mash efficiency is entered in both tools.

When I set the variable to 4%, the gravities in BF are then 2-3 points higher than on the spreadsheet. This means that if you are basing your BF efficiency on what you've learned from other tools, you will undershoot the OG estimated by BF by a couple of points.

You mention "I’ve also put in 4% grain moisture in the malt details" - and yet I can't find this option. Can you advise?
Hi @McKnuckle, I am also using a spreadsheet i based on doug293cz's original one. On that note, i cannot find the original spreadsheet... do you have a link to it? I need to read threw the details above more carefully, i would also very much like to get Brewfather match the output of the doug's spreadsheet...

For the grain moisture, it took me a while to find it! It's in the "edit fermentables" pop-up window where you enter info about the malt but it's hidden behind the "Edit Details" link

1607207255563.png



1607207347726.png
 

McKnuckle

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Well I'll be dipped... I did not know about that hidden section. Does the moisture % value actually work? I'll check it out. Thanks!

Here's Doug's spreadsheet:

 

jdudek

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Well I'll be dipped... I did not know about that hidden section. Does the moisture % value actually work? I'll check it out. Thanks!

Here's Doug's spreadsheet:

not sure! Please report. I think at some point I tested it out and it seemed like it did. But I can’t remember for sure anymore.
 

McKnuckle

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Nope, the value doesn't seem to do anything. I made a new recipe and added one grain. Then I edited the moisture % of that grain to 4%, then something stupid like 90%, then back to blank. The gravity estimates did not change regardless of the setting.

Well, at least the variable is accounted for and could be incorporated - in theory - with a bit of development.
 

jdudek

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Nope, the value doesn't seem to do anything. I made a new recipe and added one grain. Then I edited the moisture % of that grain to 4%, then something stupid like 90%, then back to blank. The gravity estimates did not change regardless of the setting.

Well, at least the variable is accounted for and could be incorporated - in theory - with a bit of development.
that’s too bad. I wish there was an official way of filing bugs or feature requests for brewfather.
 

McKnuckle

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You are right the "No Sparge" is using hot pre-boil volume by mistake, will have this corrected in the next patch. Will also add a field to set the expansion manually.
Today's new release version took care of both of these - thank you so much @skarp0ye for the super fast response to comments in this thread! The new expand/contract setting is exactly what I wished for. :mug:

Really appreciate you engaging directly with the community. Cheers
 

skarp0ye

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Today's new release version took care of both of these - thank you so much @skarp0ye for the super fast response to comments in this thread! The new expand/contract setting is exactly what I wished for. :mug:

Really appreciate you engaging directly with the community. Cheers
My pleasure, will continue looking into your feedback :)
 

jdudek

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@skarp0ye , hopefully you can incorporate the stuff from this thread so we can get the right OGs predicted by Brewfather. Thanks!
 

McKnuckle

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@jdudek, this being said, I currently have BF and Doug's spreadsheet either agreeing completely or within one gravity point. But that's with the grain water content on the spreadsheet set to 0%. Normally it's set to 4%, and that throws them off. The addition of a variable temperature correction percentage to BF, when set to 0%, has also helped normalize things.
 

jdudek

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@jdudek, this being said, I currently have BF and Doug's spreadsheet either agreeing completely or within one gravity point. But that's with the grain water content on the spreadsheet set to 0%. Normally it's set to 4%, and that throws them off. The addition of a variable temperature correction percentage to BF, when set to 0%, has also helped normalize things.
I'm interested to know how you get there....

I just tried 12lbs of pils (37 pts). It came up with 7.83 gallons of mash water and 1.053 pre boil gravity. 7.83 gallon is pretty much what the spreadsheet gives me as well, so that should be a cold volume

spreadsheet and Braukaiser formula give 1.049 for that grist in that much water for 100% conversion efficiency. If I set moisture content to 0%, I get 1.052. Still 2 points off.
 
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McKnuckle

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It's hard to troubleshoot over the forum. But you do need to have all the loss variables such as grain absorption and evaporation pretty much dead on between the two, as the margin of error is very small. Make sure to take note of the mash efficiency given in the spreadsheet and set Brewfather to that exact value. And set boil expansion to 0%, as all volumes on the spreadsheet are normalized to room temp.

Maybe we can look at a specific example via PM.
 

jdudek

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Sorry I misspoke above. I meant pre boil gravity not original gravity (I corrected the post). Losses do not matter here, I am only talking about conversion efficiency.

I reran the numbers matching exactly between BF (I had some small discrepancies). I believe you are correct @McKnuckle!

12lbs of pilsner, yield 80.13%, moisture 4%.

BH says the pre-boil gravity is 1.052 with a starting volume of 7.81 gallons.

Assuming 100% conversion, the correct pre boil gravity should be

(12 [lbs] *0.96*0.813)/((12 [lbs] *0.96*0.813) + 7.81 [gal] *8.3304 [lbs/gal] + 0.48 [lbs] ) X 100 = 12.34 P = 1.050


As you pointed out, if we remove grain moisture, then we get

(12 [lbs] *0.813)/((12 [lbs] *0.813) + 7.81 [gal] *8.3304 [lbs/gal] ) X 100 = 12.88 P = 1.052


So it would appear the only issue here is that the moisture content of the grain is ignored?? Should be an easy fix.
 

jdudek

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well actually, I kind of take that back. There's some non linear error. it works with 12lbs of grain or less... however when I try 16 lbs, pre boil gravity is over estimated by 7 pts. with 20 lbs, over estimated by 13 points.

(20 [lbs] *0.813)/((20 [lbs] *0.813) + 8.77 [gal] *8.3304 [lbs/gal] ) X 100 = 17.99 P = 1.074

BH gives a pre boil gravity of 1.087 with 8.77 gallons of mash water
 

skarp0ye

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well actually, I kind of take that back. There's some non linear error. it works with 12lbs of grain or less... however when I try 16 lbs, pre boil gravity is over estimated by 7 pts. with 20 lbs, over estimated by 13 points.

(20 [lbs] *0.813)/((20 [lbs] *0.813) + 8.77 [gal] *8.3304 [lbs/gal] ) X 100 = 17.99 P = 1.074

BH gives a pre boil gravity of 1.087 with 8.77 gallons of mash water
Can you share a recipe example of the two examples? Thanks
 

McKnuckle

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Admittedly, I would not catch such an error. I brew 1-2.5 gallon batches with no more than, say, 5 lb of grain. This is getting interesting. :)

I tried some combinations, being careful to reset the mash efficiency in BF to match what is calculated in the spreadsheet each time. The spreadsheet is set to 100% conversion efficiency, but the mash efficiency there is calculated, so you have to sync them up.

With a no-sparge 19L batch to fermenter, 1.5L/hr evaporation, and grain absorption 1L/kg, 0% heat expansion, the following figures occur (37 ppg pilsner). All of the water volumes matched. At 8 kg, the spreadsheet values begin dropping off relative to Brewfather:

Grain Weight, Mash EfficiencyBrewfather Pre-Boil, OGSpreadsheet Pre-Boil, OG
1 kg, 93.4%14, 1514, 15
2 kg, 87.5%27, 2926, 29
4 kg, 77.8%47, 5147, 51
8 kg, 63.6%77, 8476, 82
16 kg, 46.6%114, 122112, 120
32 kg, 30.4%148, 160145, 156
 
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McKnuckle

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I am suspecting that the formula used to convert Plato to SG may be slightly different between the two tools. I can get them to almost agree, within one point, if I force the spreadsheet to use the simple formula quoted below.

The simple formula is SG = 259 / (259 - ºP), which directly yields 1.xxx.

In the spreadsheet, it is GravityPoints = ºP / (258.6 - ((ºP / 258.2) * 227.1))

This yields gravity points; add 1 to make it 1.xxx.
 

jdudek

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ah... here we go, thanks @McKnuckle for pointing out the change in efficiency. I have missed the fact that if the target volume remains the same, as grain bill goes up, Lauter (and therefore mash) efficiency goes down. BF does not make that adjustment automatically, so you get answers that are way off. if you dial in the same efficiency that is predicted by the spreadsheet, then things seem to align well enough (with grain moisture set to 0).

I would argue that BF could do this better. Mash efficiency will be different for every grain bill, and a brewer cannot know it in advance (unless they do their own calculation, ie, Doug's spreadsheet). However all the variables are available to calculate it automatically and adjust gravities accordingly. It would be much nicer if if used a predictive efficiency model.

until then, if a brewer wants to get accurate values for pre boil gravity, they cannot rely in BF alone. They need another tool to predict their mash efficiency, which will vary by recipe (specifically will vary by grain/water ratio).

do we agree?
 

VikeMan

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IMO, any brewing software should offer a mash efficiency prediction tool. Users could choose to take advantage of it or not.
 

McKnuckle

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Doug's spreadsheet derives the lauter and mash efficiency from the user's provided conversion efficiency. No other popular brewing software does that, and I think it's a pretty intuitive way to break things down. Start from the top and all. That way if you do things in a consistent way process-wise, getting roughly the same conversion each time, the remaining efficiency values fall into line with the ingredients. It's a natural flow.

Maybe nobody uses conversion efficiency because the homebrew community is so brainwashed by BeerSmith with its crazy bottom-up brewhouse baseline, or maybe it's just a lack of understanding about efficiency in general. I dunno. It would require a bit of re-training.

Brewfather has a conversion efficiency input in the experimental features, but it doesn't seem to do anything useful. You can change it willy nilly and yet the downstream efficiencies remain static, which of course isn't how the numbers interact in reality. You can have BF calculate the mash eff. based on the brewhouse eff., but not based on the conversion eff.
 

VikeMan

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Doug's spreadsheet derives the lauter and mash efficiency from the user's provided conversion efficiency. No other popular brewing software does that, and I think it's a pretty intuitive way to break things down. Start from the top and all. That way if you do things in a consistent way process-wise, getting roughly the same conversion each time, the remaining efficiency values fall into line with the ingredients. It's a natural flow.

Maybe nobody uses conversion efficiency because the homebrew community is so brainwashed by BeerSmith with its crazy bottom-up brewhouse baseline, or maybe it's just a lack of understanding about efficiency in general. I dunno. It would require a bit of re-training.
FWIW, BrewCipher asks the user for mash efficiency for a given recipe. Using that, in conjunction with the user's brewhouse parameters (e.g. mash tun dead space, xfer losses, boil off rate, etc.), its mash efficiency predictor tool calculates an expected mash efficiency for any size grain bill and/or a change from batch sparge to no-sparge or vice versa.

I agree that conversion efficiency is definitely key. But, as you mentioned, most users don't know their conversion efficiency (or often, even what that means). The math can derive the conversion efficiency behind the scenes, given grain bill size, mash efficiency, and brewhouse parameters.

That said, for educational purposes, I would take Doug's stuff before all others.
 

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its strange because it seems to me that conversion efficiency is by far the easiest to understand. You put grain in water, how much sugar did you get. There are no brewhouse parameters involved. It's grain spec and water volume.
 

VikeMan

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its strange because it seems to me that conversion efficiency is by far the easiest to understand. You put grain in water, how much sugar did you get. There are no brewhouse parameters involved. It's grain spec and water volume.
Ah, but the "how much sugar did you get" includes the sugar stuck in the grain bed/dead spaces/other losses, which can't be measured directly. To determine conversion efficiency, you need to know those volumes (i.e. those brewhouse parameters), as well as the volume and gravity that actually made it to the kettle.

Conceptually, conversion efficiency is no doubt the easiest to understand. But it's not the easiest to measure. What I mean is, given the extract potential of the grains, all you need in order to calculate mash efficiency is one gravity and one volume.
 

jdudek

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Ah, but the "how much sugar did you get" includes the sugar stuck in the grain bed/dead spaces/other losses, which can't be measured directly. To determine conversion efficiency, you need to know those volumes (i.e. those brewhouse parameters), as well as the volume and gravity that actually made it to the kettle.

Conceptually, conversion efficiency is no doubt the easiest to understand. But it's not the easiest to measure. What I mean is, given the extract potential of the grains, all you need in order to calculate mash efficiency is one gravity and one volume.
I’m not sure I understand. All you need to calculate conversion efficiency is also a volume and a gravity.

if you tell me your grain bill and how much water you are mashing with + gravity of your mash, I can tell you your conversion efficiency. How does absorption or boil off come into this?
 

VikeMan

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I’m not sure I understand. All you need to calculate conversion efficiency is also a volume and a gravity.

if you tell me your grain bill and how much water you are mashing with + gravity of your mash, I can tell you your conversion efficiency.
I agree. What I was trying to get at was that you need to know those other parameters in order to figure out how much water to use in the first place. I should have been clearer.
 

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so @skarp0ye, any chance we can get a mash efficiency prediction flow (as an option) sometime in the future? I think that would put you well ahead of beer smith and presumably other brewing software.

In general, do you see the value of it based on the discussion here?
 
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