Help with low efficiency with BIAB

CaptainCookie said:

...

I tried a little experiment with the double milled. I read about the grain potential a while ago in this article of BYO (https://byo.com/bock/item/1544-understanding-malt-spec-sheets-advanced-brewing) so I tried mashing half a pound of the double milled grain in a half gallon water (PPG but at half for save some grain, should have the same result, right?)

My malt has an Extract fine grind, dry basis of 80.5%, so...
Extract Potential = 1+0.805* 0.04621 = 1037

So, mashing one pound of my malt in a gallon of water should hit 1037 gravity, right?

after the little mashing that I perform with the double milled grain, just get 1037 gravity, so, this is the answer to the problem?

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Not exactly. Most brewers don't correctly understand the definition of "points per pound per gallon" (including BrewersFriend in one of the places they do conversion efficiency calculations.) The definition is not based on water volume, but rather is based on wort volume. So that if you had one pound of grain with a potential of XX ppg, got 100'% mash efficiency, and collected one gallon of wort, you would have an SG of 1.0XX. But that one gallon of wort contains less than one gallon of water, with the balance of the volume made up of the extract from the grain. If you use one gallon of water to mash one pound of grain with a potential of XX ppg, and get 100% conversion efficiency, your wort SG will be less than 1.0XX because you will have created more than one gallon of wort. (But you couldn't actually recover all of the wort that you created because some will be retained due to grain absorption.)

Another small error comes from starting with dry extract potential, and not accounting for the typical 4% moisture content. This error is also made in both BrewersFriend and BeerSmith (unless they have been fixed since I last checked.) If your grain has a fine grind dry potential extract of 80%, then one pound of dry grain can create a max of 0.80 lb of soluble extract. However, if your grain has a moisture content of 4% (a typical value), then one lb of "as-is" grain contains only 0.96 lb of dry grain, as well as 0.04 lb of water. Thus your one lb of as-is grain only contains a max potential extract weight of 0.8 * 0.96 = 0.77 lb. If you mash one lb with one gallon of water (8.33 lb), and get 100% conversion, you will have 0.77 lb of extract, and 8.33 + 0.04 = 8.37 lb of water. This wort will have an SG in Plato of 100 * 0.77 / (0.77 + 8.37) = 8.42°P . If we convert 8.42°P to SG notation we come up with 1.0335, which is less than the 1.037 expected when using the incorrect definition.

So, I find points per pound per gallon more confusing than it's worth to most brewers. An easier way to use grain potentials is to think in terms of just points per pound. Then when dealing with wort, you think of points per gallon. To determine mash efficiency, you just divide collected wort points by total potential grain points. Collected wort points is just gallons of collected wort times the wort points per gallon. Total potential grain points is just average grain potential per pound times pounds of grain. For brewhouse efficiency, you just use the volume of wort to the fermenter rather than the volume of wort to the BK.

CaptainCookie said:

also, a just got a doubt, I have a kettle loss of about 0.22 gallons, as I perform sparge in the same kettle (don't have a mash tun just mash and sparge in the same kettle) after sparging I have this 0.22 gallons in the dead space of the kettle that I discard, using this volume won't defy the meaning of the recirculation? I mean this last wort is supposedly charged with flour of the grain and other residuals, won't this just add haze to the beer?

This question is because I just tried a little 1.85 gallon batch, with my water calculation of: (Sorry but again metric system)

2.5Kg grain bill
2.5X3=7.5 - 2.5 grain absorption = 5lts strike water
Batch size 7lts+ 3.35lts of losses = 10.35lts pre-boil (2.73gal)
Sparge water = 5.35lts

But after the sparge I got 8.5lts (2.24gal), so I guess the loss in water is due to 0.22gal after sparge that I discard plus not draining plus no squeezing

I don't make any of the procedures above to avoid any cause of haze or turbidity in the final beer

Thanks for the patience guys

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I don't understand your strike water volume calculation. Can you explain what you are doing there (I do understand you're using 1 L/kg as a grain absorption rate, so you don't have to explain that)? The strike water volume calculation involving grain absorption with which I am familiar is:And then Sparge volume is given by:
I also don't understand why you are discarding any wort after sparging. Can you explain that in more detail?

Brew on

I just started BIAB a few batches ago and have been getting around 70-75% efficiency using my mill at a .39 mil gap. I'm wondering if maybe the water pH is too high or low and that may be affecting the efficiency? I'm slowly working up to playing around with adjusting my water, but it's low on the list since the report shows it's pretty good overall. One thing I do use is Five Star's pH 5.2 Stabilizer so I don't need to worry about pH levels as much.

I hate to be the 'well, actually' guy, but 5.2 has been shown to be a joke. If your ph is 5.2 it will help keep it at 5.2 (as I understand it), but if you are at 6.7 it will NOT magically adjust it to 5.2

doug293cz said:

I don't understand your strike water volume calculation. Can you explain what you are doing there (I do understand you're using 1 L/kg as a grain absorption rate, so you don't have to explain that)? The strike water volume calculation involving grain absorption with which I am familiar is:

Strike Volume = Target First Runnings Vol + Expected Grain Absorption + MLT Undrainable Vol​

And then Sparge volume is given by:

Sparge Volume = Target Pre-Boil Vol - Target First Runnings Vol​

I also don't understand why you are discarding any wort after sparging. Can you explain that in more detail?

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Sure thing, for strike water calculation we use a factor called Filling Ratio, that is just how much water do you use per Kg of grain, the ratio is 3:1, this ratio is just for having a good amount of water soaking the grain, that's why:

2.5Kg*3= 7.5lts - grain absorption (2.5Kg) = 5lts strike water
you MLT Undrainable Vol will be my kettle dead space, a thing that I haven't considered so far, how do you calculate your Target First Runnings Vol?

I discard the wort after sparging and don't do any drainage, cuz I brew with a pal, and he freaks out about clarity and always said that left over after sparge is concentrate with flour of grain and proteins and stuff that will just cause haze in the beer, his logic is, we do recirculation for clarifying the wort, so what will be the point of clarifying the wort is you just drop all that stuff that is sedimented in the dead space of the kettle at the end of sparge? the same goes for draining, we lift the bag after sparge, all the wort that drain of the bag wasn't recirculated, ergo, not clarified, ergo, it will just add turbidity, any insight about this mess?

doug293cz said:

Another small error comes from starting with dry extract potential, and not accounting for the typical 4% moisture content.

Click to expand...

so for my malt, technically the ppg it's 10335 with a 4% moisture content, thanks a lot, I'm pretty interested in the PPG calculation and efficiency, but as you said, this calculation is based on the wort volume instead of water, I didn't quite catch up this part:

doug293cz said:

So that if you had one pound of grain with a potential of XX ppg, got 100'% mash efficiency, and collected one gallon of wort, you would have an SG of 1.0XX. But that one gallon of wort contains less than one gallon of water, with the balance of the volume made up of the extract from the grain. If you use one gallon of water to mash one pound of grain with a potential of XX ppg, and get 100% conversion efficiency, your wort SG will be less than 1.0XX because you will have created more than one gallon of wort. (But you couldn't actually recover all of the wort that you created because some will be retained due to grain absorption.)

Click to expand...

so my grain potential it's 10335, with a 100% mash conversion and collecting 1 gallon of wort I should get 10335 gravity, but it practice It's gonna be less, cuz we don't collect 100% wort, obviously, there's water in the mix too, I'm right?, also there's wort retain in the grain due to absorption, so the final gravity at the end of mashing theoretically should be less than 10335? again pretty interest in this topic

:rockin:

After looking at your crush, I'd take a look at your pH. If you can get information on your city's water and adjust accordingly with a water profile calculator, you don't really need a meter or anything. The ballpark works just fine.

CaptainCookie said:

Sure thing, for strike water calculation we use a factor called Filling Ratio, that is just how much water do you use per Kg of grain, the ratio is 3:1, this ratio is just for having a good amount of water soaking the grain, that's why:

2.5Kg*3= 7.5lts - grain absorption (2.5Kg) = 5lts strike water
you MLT Undrainable Vol will be my kettle dead space, a thing that I haven't considered so far, how do you calculate your Target First Runnings Vol?

Click to expand...

What you call "Filling Ratio" is normally referred to as "Mash Thickness" on HBT. A typical mash thickness for fly sparging is 1.25 qt/lb or 2.6 L/kg. The way your strike water equation is written, you always use 2.0 L/kg (0.96 qt/lb), which should result in a very thick mash. Doesn't seem like you would have "a good amount of water soaking the grain." My original question could be restated as: "Why are you subtracting the grain absorption from the strike water volume?"

For batch sparging, it has been shown that you get the highest lauter efficiency when each of the runnings has equal volume. So, the goal is to calculate the amount of strike water and sparge water that will give you equal volumes for first runnings and sparge runnings. Since when you sparge, the grain has already absorbed as much as it is going to, you account for grain absorption in the strike water, and ignore absorption for the sparge. The math looks like this:So, for batch sparging you shouldn't be targeting a specific mash thickness or filling ratio. This can be a benefit because it has been shown that using a higher water to grain ratio in the mash speeds up the conversion process, which can in many cases improve your conversion efficiency. And, since your ratio is quite low, this might be part of your efficiency issue.

CaptainCookie said:

I discard the wort after sparging and don't do any drainage, cuz I brew with a pal, and he freaks out about clarity and always said that left over after sparge is concentrate with flour of grain and proteins and stuff that will just cause haze in the beer, his logic is, we do recirculation for clarifying the wort, so what will be the point of clarifying the wort is you just drop all that stuff that is sedimented in the dead space of the kettle at the end of sparge? the same goes for draining, we lift the bag after sparge, all the wort that drain of the bag wasn't recirculated, ergo, not clarified, ergo, it will just add turbidity, any insight about this mess?

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Discarding wort after sparging makes no sense for any of the BIAB brewing process flows with which I am familiar. If you are really discarding your sparged wort, as you make it sound, that would really ruin your efficiency. Also, if you are just going to discard the sparged wort, why sparge in the first place. So, I guess I don't really understand the details of your brewing process. Can you provide a detailed step-by-step description of everything you do, starting with putting the strike water in the kettle, and continuing until you reach a boil?

Also, you don't need clear wort to make clear beer, and clear wort may not even make clear beer always. I squeeze the bag and have very cloudy wort, but make crystal clear beers. Most of the particulates drop out during fermentation and cold crashing. I also use gelatin as a fining agent when I keg.

CaptainCookie said:

so for my malt, technically the ppg it's 10335 with a 4% moisture content, thanks a lot, I'm pretty interested in the PPG calculation and efficiency, but as you said, this calculation is based on the wort volume instead of water, I didn't quite catch up this part:


so my grain potential it's 10335, with a 100% mash conversion and collecting 1 gallon of wort I should get 10335 gravity, but it practice It's gonna be less, cuz we don't collect 100% wort, obviously, there's water in the mix too, I'm right?, also there's wort retain in the grain due to absorption, so the final gravity at the end of mashing theoretically should be less than 10335? again pretty interest in this topic

:rockin:

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No, your dry basis grain potential really is 1.037 (calculated as 0.805 * 46.2 = 37.2 ==> 1.037.) The as-is (with moisture) potential would be 0.805 * 0.96 * 46.2 = 35.7 points/lb or 1.036 expressed as SG potential. The 46.2 is the pts/lb of sucrose, which has 100% extract potential.

The reason we ended up with only 1.0335 SG in the calculation example is that we created more than 1 gal of wort from the 1 gal of strike water. We actually had:which is within rounding error of the expected 35.7 pts for the as-is grain potential.

You are correct that we would not be able to get all of the 1.06 gal of wort separated from the grain due to the grain absorption. Grain absorption is the primary determinant of lauter efficiency, which measures how well you separate the sugar from the grain. Mash efficiency is equal to conversion efficiency times lauter efficiency. You can get 100% conversion efficiency (90% - 95% is more common), but you can never get 100% lauter efficiency because you can never get all of the wort (and thus sugar) out of the grain.

However, the grain absorption does not affect the gravity of the collected wort. The wort you drain, and the wort absorbed by the grain, have the same SG.

Brew on

doug293cz said:

What you call "Filling Ratio" is normally referred to as "Mash Thickness" on HBT. A typical mash thickness for fly sparging is 1.25 qt/lb or 2.6 L/kg. The way your strike water equation is written, you always use 2.0 L/kg (0.96 qt/lb), which should result in a very thick mash. Doesn't seem like you would have "a good amount of water soaking the grain." My original question could be restated as: "Why are you subtracting the grain absorption from the strike water volume?"

Click to expand...

Well I just come to realize how redundant it's, that's the way we were told to make the calculation, but is just straightforward as multiplicate the mash thickness, feeling dumb right now

doug293cz said:

So, for batch sparging you shouldn't be targeting a specific mash thickness or filling ratio. This can be a benefit because it has been shown that using a higher water to grain ratio in the mash speeds up the conversion process, which can in many cases improve your conversion efficiency. And, since your ratio is quite low, this might be part of your efficiency issue.

Click to expand...

I've read about it in an article in BYO, yes, gonna try this calculation with batch sparge, we were doing fly sparge, again, cuz that's the way that we were told, but, what kind of equipment will be mandatory to make a fly sparge? gonna try batch sparge, but I just want to know anyway

doug293cz said:

Discarding wort after sparging makes no sense for any of the BIAB brewing process flows with which I am familiar. If you are really discarding your sparged wort, as you make it sound, that would really ruin your efficiency. Also, if you are just going to discard the sparged wort, why sparge in the first place. So, I guess I don't really understand the details of your brewing process. Can you provide a detailed step-by-step description of everything you do, starting with putting the strike water in the kettle, and continuing until you reach a boil?

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We don't discard the sparge water, that would make all pointless, let me explain myself better as you ask

we only have a 5.3gallon (20lts) kettle, so we do the mashig, recirculation, sparge, and boiling in the same kettle, this kettle has a dead space (space between the bottom and the collection pipe) of aprox 0.21gal (0.8L) that would be our kettle trub loss

Well in detail our process after mashing is (already detail mashing in a previous post):

after the mash, we begin recirculation, we grab a sanitized bucket, open the pipe, and begin to collect some wort, then pour the collected wort back into the kettle through a skimmer for avoiding perforations in the grain bed, we repeat the process until we got a good clarified wort

then we begin to sparge, we grab a big sanitized pot (about 30lts), open the pipe, and begin to collect all the wort, at the same time we add the sparge water at 158°F into the kettle at the same rate of the run-off, again through the skimmer, after we collect all the wort, we lift the bag and there's a remaining volume of wort in the dead space of the kettle, this is the wort we discard, why we discard this? as I said before, my pal always say that the purpose of recirculation is to clarify the wort, so he believes that all this stuff that makes the wort cloudy is decanted in the dead space of the kettle, and using this left behind concentrated wort would cause haze in the beer, cuz, what would be the point of clarifying the wort in the recirculation if we pour all the cloudy stuff back into the kettle? the same with draining the bag, as we lift the bag at the end of the sparge, the drained wort of the bag wasn't recirculated, so we discarded it, so again the question, is all this right? or is just as simple as using the 100% of the wort (dead space trapped wort, drained wort from bag, squeezing the bag) and just eliminate recirculation, as it will be pointless? as you said before, cloudy wort doesn't necessarily mean cloudy beer

doug293cz said:

No, your dry basis grain potential really is 1.037 (calculated as 0.805 * 46.2 = 37.2 ==> 1.037.) The as-is (with moisture) potential would be 0.805 * 0.96 * 46.2 = 35.7 points/lb or 1.036 expressed as SG potential. The 46.2 is the pts/lb of sucrose, which has 100% extract potential.

The reason we ended up with only 1.0335 SG in the calculation example is that we created more than 1 gal of wort from the 1 gal of strike water. We actually had:

(0.77 lbs + 8.37 lbs) / (1.0335 * 8.33 lb/gal) = 1.06 gal of wort, and
1.06 gal * 33.5 pts/gal = 35.6 pts​

which is within rounding error of the expected 35.7 pts for the as-is grain potential.

Click to expand...

again, as you said before, this isn't a reliable way to calculate the efficiency? in simple terms, mashing a pound of malt in a gallon of water won't give me the answer?

CaptainCookie said:

Well I just come to realize how redundant it's, that's the way we were told to make the calculation, but is just straightforward as multiplicate the mash thickness, feeling dumb right now



I've read about it in an article in BYO, yes, gonna try this calculation with batch sparge, we were doing fly sparge, again, cuz that's the way that we were told, but, what kind of equipment will be mandatory to make a fly sparge? gonna try batch sparge, but I just want to know anyway



We don't discard the sparge water, that would make all pointless, let me explain myself better as you ask

we only have a 5.3gallon (20lts) kettle, so we do the mashig, recirculation, sparge, and boiling in the same kettle, this kettle has a dead space (space between the bottom and the collection pipe) of aprox 0.21gal (0.8L) that would be our kettle trub loss

Well in detail our process after mashing is (already detail mashing in a previous post):

after the mash, we begin recirculation, we grab a sanitized bucket, open the pipe, and begin to collect some wort, then pour the collected wort back into the kettle through a skimmer for avoiding perforations in the grain bed, we repeat the process until we got a good clarified wort

then we begin to sparge, we grab a big sanitized pot (about 30lts), open the pipe, and begin to collect all the wort, at the same time we add the sparge water at 158°F into the kettle at the same rate of the run-off, again through the skimmer, after we collect all the wort, we lift the bag and there's a remaining volume of wort in the dead space of the kettle, this is the wort we discard, why we discard this? as I said before, my pal always say that the purpose of recirculation is to clarify the wort, so he believes that all this stuff that makes the wort cloudy is decanted in the dead space of the kettle, and using this left behind concentrated wort would cause haze in the beer, cuz, what would be the point of clarifying the wort in the recirculation if we pour all the cloudy stuff back into the kettle? the same with draining the bag, as we lift the bag at the end of the sparge, the drained wort of the bag wasn't recirculated, so we discarded it, so again the question, is all this right? or is just as simple as using the 100% of the wort (dead space trapped wort, drained wort from bag, squeezing the bag) and just eliminate recirculation, as it will be pointless? as you said before, cloudy wort doesn't necessarily mean cloudy beer



again, as you said before, this isn't a reliable way to calculate the efficiency? in simple terms, mashing a pound of malt in a gallon of water won't give me the answer?

Click to expand...

Thanks, I think I have a good understanding of your process now. It is really just a variation on a traditional 3 vessel process, except that a single vessel is used for both MLT and BK. In this case your 0.8 L of undrainable volume affects both the mash losses and the BK to fermenter losses.

I did some single, double, and triple batch sparge simulations for your grain bill, and pre-boil volume, using both your 0.8 L undrainable and also 0 undrainable volumes. With your system plus undrainable, the single batch sparge gives 76.4% lauter efficiency, double is 79.7%, and triple is 81.2%. I can't simulate fly sparging (the dynamics and variables are way too complex) but a fly sparge is basically equivalent to a very large number of very small sparges. As you can see each additional batch sparge step gives less and less improvement, thus with a perfectly done fly spage you would be hard pressed to do better than about 83% efficiency. If you eliminated your undrainable volume the corresponding lauter efficiencies would be 78.8%, 82.0%, and 83.4%. A perfect fly sparge in the 0 undrainable case could give you about 85%.

I did some strike temp calcs with your grain bill and low strike water volume, and your 167°F strike temp is not out of line. You shouldn't be doing any significant damage to your enzymes due to your strike temp.

I believe a big part of your efficiency problem is because of your sparge process, and drain configuration on your vessel. For a good fly sparge, you want to start with 1 - 2" of wort above the grain bed, and maintain that until you have added all of your sparge water. Given your very low filling ratio (mash thickness) I'm not sure you will have an adequate amount of wort above the grain bed. If this is the case, then you are likely to get channeling, even though you try to distribute the sparge water across the surface of the mash.

Another issue with your sparge process is its speed. You should try to extend your sparge time to 30 minutes to minimize channeling. This is especially true since you have a side pickup in your vessel with no false bottom. This encourages a flow pattern thru the grain bed that wants to bypass the lower part of the bed that is away from the pickup.

For your equipment configuration, I think you would get much better results by batch sparging. The basic steps are:

• Stir mash well at the end of the mash time
• Vorlauf (recirculate) if you want, but it's not really necessary when using a bag
• Completely drain all of the wort, as fast as your system will allow without sticking the lauter
• Add your sparge water and stir well for about 5 minutes
• Vorlauf (recirculate) if you want
• Completely drain all of the wort, as fast as your system will allow
• Start the boil (with a separate MLT and BK, heating to a boil can start after the first runoff)

Remember that:And all of the above discussion is only about lauter efficiency.

The conversion efficiency in your mash can be measured in real time using the method described here. Anything better than 90% is OK, better than 95% is good, and above 98% is great.

There are a number of on-line calculators that will do a good job of calculating your mash efficiency grain bill, pre-boil SG, and pre-boil volume, or from your grain bill, post-boil SG (i.e. OG), and post-boil volume. (If you want the details on doing the calculation using points, just ask.) Once you have your mash and conversion efficiencies, you can calculate your lauter efficiency as:
Brew on

doug293cz said:

Thanks, I think I have a good understanding of your process now. It is really just a variation on a traditional 3 vessel process, except that a single vessel is used for both MLT and BK. In this case your 0.8 L of undrainable volume affects both the mash losses and the BK to fermenter losses.

I did some single, double, and triple batch sparge simulations for your grain bill, and pre-boil volume, using both your 0.8 L undrainable and also 0 undrainable volumes. With your system plus undrainable, the single batch sparge gives 76.4% lauter efficiency, double is 79.7%, and triple is 81.2%. I can't simulate fly sparging (the dynamics and variables are way too complex) but a fly sparge is basically equivalent to a very large number of very small sparges. As you can see each additional batch sparge step gives less and less improvement, thus with a perfectly done fly spage you would be hard pressed to do better than about 83% efficiency. If you eliminated your undrainable volume the corresponding lauter efficiencies would be 78.8%, 82.0%, and 83.4%. A perfect fly sparge in the 0 undrainable case could give you about 85%.

Click to expand...

Sweet thanks, could you please share the simulation's math? I'm pretty fond of the beer's maths, also how can I make up for a triple batch?

I'm currently working with 2 batches, a 17lts batch for my normal beer, a red ale, and 7lts for my experiments with new varieties, sorry for using metric system, but I'm more used to it

For the 17lts batch, my target pre-boil is 20lts, the capacity of my kettle, accounting:
-1lt kettle loss
-1lt boil-off
-1lt fermenter loss
but now, I should account 0.8lts sparge loss plus 0.5lts drainage loss (in the case of discarding the dead space after sparge and no performing a bag drainage), I'm right? gonna try to convince my pal to make use of this wasted wort

anyway just accounting with the 20lts pre-boil (5Kg grain bill), for the batch sparge will be:

Tgt vol: 20/2= 10lts
Sparge vol: 10lts
Strike vol: 10+5+0.8= 15.8lts
this calculation will be with only one sparge (10lts), but if I wanna do a double batch, I just pour another 10lts? the same for a third batch? the same goes for a 7lts batch (10lts pre-boil)?

doug293cz said:

There are a number of on-line calculators that will do a good job of calculating your mash efficiency grain bill, pre-boil SG, and pre-boil volume, or from your grain bill, post-boil SG (i.e. OG), and post-boil volume. (If you want the details on doing the calculation using points, just ask.)

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Please, I hate being a pain in the ass, but please I would love to have the detailed calculation using points, I think that just using online calculator is just no fun

CaptainCookie said:

Sweet thanks, could you please share the simulation's math? I'm pretty fond of the beer's maths, also how can I make up for a triple batch?

Click to expand...

I have previously posted a description of the simulation here.

Beer club tonight. I'll try to respond to your other questions/requests on Saturday.

Brew on

doug293cz said:

I have previously posted a description of the simulation here.

Beer club tonight. I'll try to respond to your other questions/requests on Saturday.

Brew on

Click to expand...

I'll be looking forward it, Cheers!

CaptainCookie said:

Sweet thanks, could you please share the simulation's math? I'm pretty fond of the beer's maths, also how can I make up for a triple batch?

I'm currently working with 2 batches, a 17lts batch for my normal beer, a red ale, and 7lts for my experiments with new varieties, sorry for using metric system, but I'm more used to it

For the 17lts batch, my target pre-boil is 20lts, the capacity of my kettle, accounting:
-1lt kettle loss
-1lt boil-off
-1lt fermenter loss
but now, I should account 0.8lts sparge loss plus 0.5lts drainage loss (in the case of discarding the dead space after sparge and no performing a bag drainage), I'm right? gonna try to convince my pal to make use of this wasted wort

anyway just accounting with the 20lts pre-boil (5Kg grain bill), for the batch sparge will be:

Tgt vol: 20/2= 10lts
Sparge vol: 10lts
Strike vol: 10+5+0.8= 15.8lts
this calculation will be with only one sparge (10lts), but if I wanna do a double batch, I just pour another 10lts? the same for a third batch? the same goes for a 7lts batch (10lts pre-boil)?

Click to expand...

When doing double or triple batch sparges, the strike water to grain ratio can get rather small, which would lead to overly thick mashes, which can lead to difficulty when mashing in, and conversion efficiency drops. The same can happen with single batch sparges involving large grain bills. So, to avoid overly thick mashes the math gets a little more complicated, but still pretty simple. First calculate two target strike volumes as follows:
Then your actual strike volume should be:You then calculate the sparge volumes (all the same) as:Then make sure the run off volume after each sparge is the same as the sparge volume (i.e. you shouldn't see any additional grain absorption during the sparge steps.)

When doing multiple batch sparges for lower OG beers, you can be at risk for over sparging (sparge runnings SG about 1.010 or lower), which can cause tannin and silicate extraction. To minimize the potential for tannin/silicate extraction you should acidify your sparge water to a pH of 5.8 or lower. You can also use the simulation method linked in my previous post to estimate the SG of your last sparge run off, and if it is less than 1.010, then use fewer sparge steps.

CaptainCookie said:

Please, I hate being a pain in the ass, but please I would love to have the detailed calculation using points, I think that just using online calculator is just no fun

Click to expand...

Don't worry about asking lots of questions. I am happy to provide whatever knowledge I can to people genuinely interested in learning.

To calculate efficiencies by points, start by calculating the total potential points of your grain bill:If you want to correct for the moisture content of the grain then multiply the total potential points by (1 - %Moisture / 100%). Most brewing software does not correct for moisture, so if you want your calcs to match, then don't correct for moisture.

Mash efficiency is calculated as:If you conduct a sparge, then you need to mix all the wort extremely well before taking the SG sample, since the wort will have significant levels of SG stratification after combining the different run offs. You can also calculate mash efficiency after the boil as follows:If you didn't add sugar during the boil, then the pre-boil and post-boil mash efficiencies should be the same. If you added sugar, the post-boil formula ignores the volume of the sugar added during the boil, so the post-boil calculation will be slightly lower than the pre-boil calculation. The amount of error will depend on just how much sugar was added during the boil.

Your brewhouse efficiency can be calculated as:Note that if sugar was added during the boil, then your brewhouse efficiency can actually be higher than your mash efficiency. If no sugar was added during the boil, then the brewhouse efficiency has to less than or equal to the mash efficiency.

Brew on

Thanks a lot, this is really what I was looking for, just one last question

doug293cz said:

Mash efficiency is calculated as:
Total Collected Wort Points = Pre-Boil Wort Points/gal * Gallons of Wort in BK Pre-Boil
Mash Efficiency = 100% * Total Collected Wort Points / Total Potential Points
If you conduct a sparge, then you need to mix all the wort extremely well before taking the SG sample, since the wort will have significant levels of SG stratification after combining the different run offs. You can also calculate mash efficiency after the boil as follows:
Total Collected Points from Mash = Post-Boil Wort Points/gal * Gallons of Post-Boil Wort in BK - Sugar Points Added During Boil
Mash Efficiency = 100% * Total Collected Points from Mash / Total Potential Points

Click to expand...

I get it all now, but what do you refer with "Pre-Boil Wort Points/gal" and "Post-Boil Wort Points/gal" and how do you calculate them? that's the only thing I don't get it, sorry for the dumb question. thanks

CaptainCookie said:

Thanks a lot, this is really what I was looking for, just one last question



I get it all now, but what do you refer with "Pre-Boil Wort Points/gal" and "Post-Boil Wort Points/gal" and how do you calculate them? that's the only thing I don't get it, sorry for the dumb question. thanks

Click to expand...

Points/gal = (SG - 1) * 1000, so an SG of 1.045 is just 45. Works just like points/lb when grain potentials are given in SG form.

Brew on

I love BIAB! FWIW, I have a Grainfather and a three kettle rig but always steer to doing BIAB. I squeeze the life out of my brew bag to drain the excess wort and when done I move the bag of grains to a smaller pot or cooler and whatever else drains is added to the kettle before or during boil. Never had a haze issue with my brews nor "tannins extraction". I cold crash which clears up any haze unless I'm doing a NEIPA. My efficiency ranges from 70-80% and I believe the lower end was due to not using a calc to understand how much strike water was needed. I always assumed starting with 8gal of water for a 5 gal batch was "okay" lol

TheBrewBrotha said:

I love BIAB! FWIW, I have a Grainfather and a three kettle rig but always steer to doing BIAB.

Click to expand...

So far I can see that BIAB it's pretty more easy to handle, I always had a question, it's valid to stir the grain during mashing? do it increase the conversion rate? what about recirculation? do you do it? so far I've seen that it's pointless in BIAB

Hey doug293cz, I had checked the link that you give me:

doug293cz said:

The conversion efficiency in your mash can be measured in real time using the method described here. Anything better than 90% is OK, better than 95% is good, and above 98% is great.

Click to expand...

and about the formula of FWmax:


I'm guessing that Egrain it's the Extract fine grind, dry basis, right? and what It's value when I'm working with differents grains? in an Imperial stout gonna have like 3 differents Egrains values, thanks

CaptainCookie said:

and about the formula of FWmax:

FWmax= 100% * Mgrain * Egrain/(Vmash_water + Mgrain * Egrain)​

I'm guessing that Egrain it's the Extract fine grind, dry basis, right? and what It's value when I'm working with differents grains? in an Imperial stout gonna have like 3 differents Egrains values, thanks

Click to expand...

It would be the weighted average.

10 lbs at 85% + 2 lbs at 70% = ( 10*.85 + 2 * .7 ) / 12 = 82.5%

CaptainCookie said:

So far I can see that BIAB it's pretty more easy to handle, I always had a question, it's valid to stir the grain during mashing? do it increase the conversion rate? what about recirculation? do you do it? so far I've seen that it's pointless in BIAB

Click to expand...

Stirring (or recirculation) can help break up the gelatinized layer on the surface of the grits, allowing water better access to the less/non-gelatinized starch under the gelatinized layer. This will speed up the overall gelatinization process, and thus the conversion rate. Stirring should be more effective than recirculation since it can provide higher shear velocities at the surface of the grits.

That said, the smaller the grits (the finer the crush) the less effect stirring/ recirculation will have on the conversion rates.

Recirculation in BIAB is unnecessary in cases where the bag occupies the full volume of the kettle. In cases where the bag is in a basket (or there is just a mesh basket) the volume of wort under and around the basket does not really interact with the grain, and diffusion of sugar out of the constrained grain mass into the "free" volume is fairly low, and stirring doesn't do much to mitigate this effect. To maximize lauter efficiency, you want all your wort to be homogeneous w.r.t. sugar concentration, but with a basket the wort outside the basket will be lower in sugar concentration, and the wort that is absorbed by the grain during lautering will have higher concentration. Recirculation of the wort during the mash will homogenize the wort concentration, so is desirable when using a basket.

CaptainCookie said:

Hey doug293cz, I had checked the link that you give me:


and about the formula of FWmax:

FWmax= 100% * Mgrain * Egrain/(Vmash_water + Mgrain * Egrain)​

I'm guessing that Egrain it's the Extract fine grind, dry basis, right? and what It's value when I'm working with differents grains? in an Imperial stout gonna have like 3 differents Egrains values, thanks

Click to expand...

In the case of multiple grain potentials, Egrain is just the weighted average of the individual Egrain values. It turns out that:Braukaiser's formula only works in metric units, when 1 L of water = 1 kg of water. If using imperial units then the equation becomes:Where volume is in gallons and density of water is 8.33 lb/gal (@ 68°F / 20°C.)

Brew on

CaptainCookie said:

So far I can see that BIAB it's pretty more easy to handle, I always had a question, it's valid to stir the grain during mashing? do it increase the conversion rate? what about recirculation? do you do it? so far I've seen that it's pointless in BIAB

Click to expand...

I only recirculate when using the Grainfather as it's recommended for many reasons. Also I personally stir 1-2x when mashing in a GF. When I do BIAB I don't recirculate much, maybe a quick vorlof and I never stir the mash.

I've been checking the lautering efficiency and got a couple questions, about it:

For a double batch sparge (2 sparge steps) the efficiency would be:

and the overall lauter effiency would be:
do I'm right?? also squeezing the bag won't affect the Vgrain_absorption??

and about this formula
the extract is no more than "mgrain * egrain", right, just gonna be sure to get it all right

CaptainCookie said:

I've been checking the lautering efficiency and got a couple questions, about it:

For a double batch sparge (2 sparge steps) the efficiency would be:

Eff_1st_runoff= 100% * V_1st_runoff / (V_1st_runoff + Vgrain_absorption + Vdead_space)
Eff_2nd_runoff= (100% - Eff_1st_runoff) * V_2nd_runoff / (V_1st_runoff + Vgrain_absorption + Vdead_space)
Eff_3th_runoff= (100% - Eff_1st_runoff - Eff_2nd_runoff) * V_3th_runoff / (V_1st_runoff + Vgrain_absorption + Vdead_space)
​

and the overall lauter effiency would be:

Lautering efficiency = Eff_1st_runoff + Eff_2nd_runoff + Eff_3th_runoff
​

do I'm right?? also squeezing the bag won't affect the Vgrain_absorption??

and about this formula

mextract_left_in_lauter = (Vwater_added + Vgrain_absorbed) * sg * extract
​

the extract is no more than "mgrain * egrain", right, just gonna be sure to get it all right

Click to expand...

I really admire Kai Troester's writings, and I have probably learned more from him about brewing than any other single author. But that said, I find some of his formulas and derivations somewhat obtuse and difficult to follow, and the lauter efficiency exposition I find very confusing myself. I mean no disrespect to Kai, and others may find his formulas more intuitive than I do. So, let's forget what Kai says about lauter efficiency, and start from scratch. This may or may not be better than Kai's approach, but I find it easier to follow.

Also, sorry for the delayed response, but I knew this post was going to require significant effort and time, so I put it off until it was more convenient for me.

All of the equations/formulas given below are valid in both imperial and metric units, which is not the case for those give by Troester. Any volumes involved should all be thermal expansion adjusted to a constant temperature, and for reasons I won't go into, 68°F (20°C) is recommended. The density of water at 68°F (20°C) is 8.33 lb/gal or 0.9982 kg/L.

Let's start by reviewing the general definition of efficiency, that applies to pretty much anything:
The equation above is for fractional efficiency, and to convert to percent efficiency you multiply fractional efficiency by 100%. When multiplying efficiencies it is necessary to work with fractional efficiencies, so percentage efficiencies need to be divided by 100% before multiplying.

When it comes to brewing efficiency, the "Amounts" we are interested in are Weights of Extract. Extract is mostly sugar (including dextrines), but also contains proteins, and many other minor components. In some cases we can use volumes in the efficiency formulas if the concentration of the liquid is the same for the numerator and denominator. Gravity points, which are just a proxy for weight, can also be used in many cases.

So let's look at some definitions for some of the efficiencies of interest in brewing. Unfortunately, the terms used by different authors and in different segments of brewing are not always the same, which can lead to confusion. But, if you truly understand the definitions and concepts, you can usually determine what a particular author is referring to. In the following definitions and formulas, Extract always refers to Extract_Weight. Modifiers will be used to describe which particular Extract_Weight is being referenced.

Conversion Efficiency is defined as:Total_Potential_Extract is the sum of the extract potentials for each of the items in the grain bill, i.e.:Where Yield_Potential is the dry basis, fine grind fractional yield potential for each grain, usually about 0.8 or 80% for base grains. Since most grains have about 4% moisture, the as-is weights should be multiplied by 0.96 (or whatever the appropriate value is for actual moisture content) to obtain the most accurate extract potentials (although many calculators neglect to do this.)

Lauter Efficiency is defined as:Or fraction of the extract created in the mash that makes it into the boil kettle.

Mash Efficiency is defined as:
Brewhouse Efficiency is defined as:
In order to actually calculate any of the efficiencies above, we need to be able to measure the weight of the extract at various points in the process. But, measuring extract weight in a solution is difficult, so what can we do instead? Two items that are relatively easy to measure are volume and specific gravity (SG), and it turns out we can use these two values to calculate extract weight, as well as water weight in any volume of wort.Once we know the wort weight, we can determine the extract weight if we know the weight percent of extract in the wort. It turns out that weight percent (Wt%) of extract is just the °Plato (°P):And there is an equation that we can use to convert SG to °P, which is:To calculate the Extract in a volume of wort, we need to know the SG and wort volume. From there we calculate the °P of the wort (using Eq 14), and the wort_weight (using Eq. 10). Now calculate Extract and water weight, using:
Calculating Conversion Efficiency

The first efficiency we are interested in is the Conversion Efficiency, so we need to determine Extract Created in Mash and Total Potential Extract. We calculate Total Potential Extract from Eq. 3. To get Extract Created in Mash we will need to solve Eq. 12 for Extract:We measure the SG of the wort at the end of mash (after aggressive stirring or recirculation to insure that the SG is uniform throughout) and use Eq. 14 to determine the °Plato of the wort in the mash. Eq. 8 to Eq. 11 are equally valid for water if we change "Wort" to "Water" and SG = 1, So, we use Eq. 8 and the strike water volume to calculate the Water Weight in mashAnd then use Eq. 17 to calculate the Extract Created in Mash:Once we have both the Total Potential Extract and Extract Created in Mash, we calculate the Conversion Efficiency using Eq. 2:
Calculating Lauter Efficiency

Calculating lauter efficiency is where my thinking parts ways with Troester's. Troester goes thru calculating a "lauter step efficiency" for each run-off (initial plus sparge(s).) I believe the step efficiency concept to be useless in practice, and not worth calculating. My reasons are that what you really want to be able to do is compare results across no-sparge, single batch sparge, multiple batch sparge, and fly sparge processes. But, a no-sparge lauter efficiency will always be better than the initial run-off step lauter efficiency from a batch sparge, but the eventual lauter efficiency of a batch sparge will always be better than a no-sparge (assuming equal pre-boil volumes.) So, comparing step efficiencies provides no useful information, nor does it help with recipe calculations. To get useful information, you have to compare efficiencies at the end of the full lauter process. Plus it's simpler to just calculate the efficiency for the full lauter process than calculating individual steps.

For lauter efficiency we need to know Extract in BK and Extract Created in Mash. We calculated Extract Created in Mash above when determining conversion efficiency. To calculate Extract in BK we will make use of Eq. 10, 14 & 15. First we calculate Wort Weight in BK with Eq. 10:Next determine the wort's °P with Eq. 14:Next calculate the Extract_in_BK using Eq. 15:And finally we calculate Lauter Efficiency using Eq. 4:
Calculating Mash Efficiency

Mash Efficiency can be calculated using either Eq. 5 or Eq. 6, since we calculated the required factors while calculating Conversion Efficiency and Lauter Efficiency. An approximate way to calculate mash efficiency is to divide gravity points in BK by total potential points. In this case gravity points in BK is a proxy for Extract in BK, and total potential points is a proxy for Total_Potential_Points, where there are approximately 46 gravity points per pound of extract.

Calculating Brewhouse Efficiency

To calculate Brewhouse Efficiency, we start by calculating Extract in Fermenter the same way we did for Extract in BK in the Lauter Efficiency section. We then calculate Brewhouse Efficiency using Eq. 7:You can also calculate brewhouse efficiency approximately by dividing gravity points in fermenter by total potential points.

Squeezing

Squeezing does affect the grain absorption, since if you get more wort out of the mash, there is less wort left behind. If you get more wort out you also get more extract out, so lauter efficiency, mash efficiency, and brewhouse efficiency are all increased.

Brew on

The method psoted above by Doug, what I call the “extract weight” method is the *correct* way to calculate these. However, there’s another way that is very close ~0.2% difference that is IMO much simpler.

I call this method total gravity points. Really the only complicated part is the correction formula for measuring conversion efficiency, where the wort volume must be calculated. You cannot use water volume for conversion, despite many software doing so. Most notably being brewers friend, which results in a conversion efficiency ~8% lower than it should be.

All volumes are in reference to room temperature volume, and all gravity readings should be taken at room temperature, ie do not trust a hydrometer temperature correction tool.

The general outline being

Measuring Efficiencies

Efficiency = Total_Gravity_Points_Actually_Obtained / Maximum_Amount_Available

Where Total_Gravity_Points = Wort_Volume * Specific_Gravity
And

Total_Potential_Points = GrainWeight * GrainPPG
Total_Potential_Points = 12 lb * 36 PPG = 432 points

Before we do conversion efficiency, I must first outline the formula for calculating the wort volume from the mash conditions, which is actually quite easy.

GetWortVolumeFromSG(WaterVolume,GrainWeight,GrainPPG,SG)
{
WortWeight = WaterVolume * 8.3304 + GrainWeight * GrainPPG / 46;
WortVolume = WortWeight/(SG*8.3304);
}

Example
GetWortVolumeFromSG(5.25 gallons , 12 lb, 36 ppg , 1.069)
{
WortWeight = 5.25 * 8.3304 + 12 * 36 / 46 = 53.126 lb;
WortVolume = WortWeight / (1.069 * 8.3304) = 5.963 Gallons;
}

Note that the wort volume in the mash is ~0.693 gallons higher than the strike water used, this is due to the volume displaced when the sugar, proteins, and starches dissolve into the water.

Conversion Efficiency is defined as the fraction of the extract converted during the mash to the total potential extract of the grains.

Total_Mash_Points = WortVolume * WortGravity = 411.44
Conversion_Efficiency = WortVolume * WortGravity / Total_Potential_Points
Conversion_Efficiency = 5.963 * 69 / 432 = 411.44 / 432 = 95.24%

note the slight loss of accuracy, but the much simpler math.



Lauter Efficiency is defined as the fraction of the extract converted during the mash that makes it into the kettle.

Lauter_Efficiency = Extract_in_BK / Total _Mash_Points
Lauter_Efficiency = PreboilVolume * PreboilGravity / 411.44
Lauter_Efficiency = 6.70 * 54.57 / 411.44 = 0.8886 = 88.86%



Mash Efficiency is defined as as the fraction of the total potential extract that makes it into the Kettle.

Mash_Efficiency = PreboilVolume * PreboilGravity / Total_Potential_Points
Mash_Efficiency = 6.70 * 54.57 / 432 = 84.63%

OR
Mash_Efficiency = Conversion_Efficiency * Lauter_Efficiency
Mash_Efficiency = 88.86 % * 95.24% = 84.63%

Brewhouse Efficiency is defined as the fraction of the total potential extract that makes it into the fermenter.


Lets assume 1 gallon boil off, so that
OG = preboil gravity points / PostboilWortVolume
OG = 365.62 / 5.7 gallons = 64.14

And batch size (volume into fermenter )
Batch Size = 5.7 gallons – 0.5 gallons = 5.2 gallons

and 0.5 gallons kettle loss.

Brewhouse_Efficiency = Extract_in_Fermenter /Total_Potential_Points
Brewhouse_Efficiency = Wort_Volume_In_Fermenter * OG /432
Brewhouse_Efficiency = 5.2 * 64.14 /432 = 77.2%
Alternatively:
Brewhouse_Efficiency = MashEfficiency * Batch_Size / ( BatchSize + Kettle_Loss)
Brewhouse_Efficiency = 84.63 * 5.2 / ( 5.2 + 0.5) = 77.2%

I'll do another post soon for how to predict efficiencies using this method. I like this method for several reasons, it uses measurements everyone should already be taken, doesn't require any unit conversions, and the math is much simpler. The one down side is the marginal loss in accuracy, but it's really quite small, and is much less than the precision we have given our methods of measuring gravity and volume.

Predicting Efficiencies, and specific gravities.

We will have a couple general functions to make our lives easier, which are only necessary for mash steps. After the initial mash is done, and no more grains are undergoing conversion, it’s just a matter of tracking wort volume, and total gravity points.

Apologies again for the sig-figs, they’re being used for demonstration.

Remember from the previous post that


PPG of sucrose is 46 gravity points per pound of sugar per gallon of resultant wort, and remember that the sugar increases volume so this is not equivalent to 1 lb of sugar in 1 gallon of water, but ~0.98^1 ish gallons of water.^1 didn’t do the math to check, but it’s around there.

For mash steps where an infusion of water is added, such as the initial strike, or an additional water infusions, we have to account for increases in Wort Volume where the total water added to the mash, and the increased volume created by the sugar is tracked. Use the function GetWortVolumeFromSG to calculate this.

Conversion Efficiency is defined as the fraction of the extract converted during the mash to the total potential extract of the grains.

As such, Mash SG is directly proportional to the conversion efficiency by using the formula below (credit to @Doug293cz and @Braukaiser). There’s no way to predict conversion efficiency, but assuming mash pH and crush does not change, it’s pretty consistent for most brewers. Overly thick mashes tend to suffer due to osmotic pressure, and decreasing surface area of the grain kernel (decreasing gelatinization).

function PredictMashSG(
WaterVolume,GrainWeight,GrainPPG,ExpectedConversionEfficiency
)

and

function ConvertPlatoToSG(Plato)



Example
function PredictMashSG(6 gallons, 12 lb , 36 PPG ,100%)



Then

Wort Volume * MashSG = MashTotalPoints.
6.69 * 64.54134049 = 431.998977


100 * MashTotalPoints / TotalGrainPoints = Conversion Efficiency

431.998977/ 432 = 99.99976%%

#Note the very slight loss of accuracy here. This loss increases as the amount of SG increases, for a 25 lb batch it’s 99.434… %. This ends in a total OG of ~1.100 – 1.120 for most brewers so that’s sort of a worst case scenario. This very slight loss of accuracy is much less than the instrumental uncertainty.

The rest are fairly straight forward, just a dilution of wort volume and total gravity points.

Continued example
We have an absorption rate of 0.125 gal/lb (Typical for mashtun brewers)

1stRunoffSG = MashSG
1st run off volume = MashWaterAdded – Absorption rate = 4.5 gallons
1stRunoffPoints = Volume * SG = 4.5 * 64.54… = 290.4… Gravity Points
Retained Wort Volume is then 6.69 – 4.5 = 2.19.. gallons
retained wort gravity points = 2.19 * 64.54 = 141.56
//Sanity check!
432 – 290.4 = 141.6 CHECK

Sparge with 1.71 gallons for a total water used of 1.71 gallons. SpargingWortVolume = 2.19 + 1.71 = 3.9 gallons
2ndRunoffSG = retained wort gravity points / SpargingWortVolume
2ndRunoffSG = 141.56 / 3.9 = 36.266…. = 1.0363
2ndRunoffVolume = 1.71 gallons
Note: Since the grains are saturated, there’s no further absorption.
2ndRunoffPoints = Volume * SG = 1.71 * 36.26… = ~62.01… Gravity Points
PreboilGravityPoints = 1st + 2nd RunOffPoints = 62 + 290.4 = 352.4
and again,
SG = GravPoints / WortVolume
= 352.4 / 6.75 gallons = 1.05676 SG


Lauter efficiency = Total Points in preboil / Total points in mash
Lauter efficiency = 100 * 352.4 / 432 = 81.57 %
Mash Efficiency = Total Points in preboil / Total points in grain
Brewhouse efficiency = Total points in fermenter / total points in grain


As you can see, besides the initial mash steps, using this method is relatively easy. All you have to do is track wort volume, and gravity points which is some simple algebra.

Sweet, thank you guys, gonna check it up and post later on any doubts, hope that I can count with you with any further question over others math topics

...for the sake of keeping it simple -- I just worked with my water chemistry tonight and bumped mash efficiency over 5 points...