Am I doing this right?

[Vintage Iron]

Just curious if I'm doing this BIAB correctly. Below are a couple pics of the rudimentary set up. (excuse my terminology if the wording is wrong, I'm rather GREEN at this)

Mashing @ 152deg per the recipe. After the 60 min mash, sparging with about a 1.5 gal of 170 water for about 10min, (white plastic container) then give the grain bag a squeeze.

Is there anything I'm doing wrong here? The latest batch (NB's "Dead Ringer IPA) yielded a 1.050 initial gravity on a 5 gal kit, so it seems as though all is well but I'm curious if you see anything in the pics that could be done "better".

Thanks!

 

[FloppyKnockers]

IMO, sparging is a waste of time and contradictory to the simplicity of BIAB. People do it... I've done it once, but I went back to simple and lazy. That said - it looks like you're doing everything just fine. You might just end up with some beer in a couple weeks.

 

[LittleRiver]

Looks good.

If you're relying on your grain supplier to crush your grains (i.e. a relatively coarse crush), then sparging will help with your efficiency. Once you get your own mill, you can crush fine enough that sparging will become optional.

I have my mill set at .025" and get ~83% efficiency, so I don't bother sparging.

 

[LostHopper]

I heard one of the Aussie brewers who was an early advocate of full volume BIAB call the method "passive sparge" rather than no sparge.
I'm not trying to start a semantics debate but thought it was interesting and consistent with Floppy's post.

 

[Vintage Iron]

Looks good.

If you're relying on your grain supplier to crush your grains (i.e. a relatively coarse crush), then sparging will help with your efficiency. Once you get your own mill, you can crush fine enough that sparging will become optional.

I have my mill set at .025" and get ~83% efficiency, so I don't bother sparging.

Not to derail my own thread, but I've seen people post efficiency numbers. How is that calculated? (Again, relative newbie here)

 

[mongoose33]

@Morrey and I did some work with this--the idea was that squeezing was analogous to sparging in that you're wringing out the residual wort, either mechanically by squeezing or by rinsing (sparging).

We didn't see there as being much if any difference, so do what feels good.

 

[RM-MN]

IMO, sparging is a waste of time and contradictory to the simplicity of BIAB. People do it... I've done it once, but I went back to simple and lazy. That said - it looks like you're doing everything just fine. You might just end up with some beer in a couple weeks.

Sparging always gets you more of the sugars for fermenting and thus improves efficiency. Whether you consider it worth your effort is up to you.

Looks good.

If you're relying on your grain supplier to crush your grains (i.e. a relatively coarse crush), then sparging will help with your efficiency. Once you get your own mill, you can crush fine enough that sparging will become optional.

I have my mill set at .025" and get ~83% efficiency, so I don't bother sparging.

If you are getting a relatively coarse crush from your LHBS there are 3 things that can help improve efficiency.
1. Mash longer. It takes time for the water to get into the grain particles and gelatinize the starches so they can be converted. Try 90 to 120 minutes and see if you get better efficiency.
2. Sparging always gets more of the sugars from the grain. It also adds another step so you have to decide if it is worthwhile of if it would be easier to just buy more grain.
3. Dump your LHBS and buy your own mill. Now you have control of how fine the grain is milled and you can buy grain in bulk for the cost savings which can be quite substantial being that the grain is cheaper in bulk and you will use less of it if you can get it milled fine.

 

[Vintage Iron]

I heard one of the Aussie brewers who was an early advocate of full volume BIAB call the method "passive sparge" rather than no sparge.
I'm not trying to start a semantics debate but thought it was interesting and consistent with Floppy's post.

So it sounds like the consensus is that there is no consensus on sparge vs no sparge. I think I'll keep doing it because I was amazed at how much "wort" came off the grain during the sparge. That extra 1.5 gal of water was just as dark looking as the rest of the wort. All of that sweet goodness would have been lost w/o a sparge.

 

[mongoose33]

So it sounds like the consensus is that there is no consensus on sparge vs no sparge. I think I'll keep doing it because I was amazed at how much "wort" came off the grain during the sparge. That extra 1.5 gal of water was just as dark looking as the rest of the wort. All of that sweet goodness would have been lost w/o a sparge.

But not if you squeezed. You're not going to see a material difference if you sparge or if you squeeze.

 

[Bobby_M]

So it sounds like the consensus is that there is no consensus on sparge vs no sparge. I think I'll keep doing it because I was amazed at how much "wort" came off the grain during the sparge. That extra 1.5 gal of water was just as dark looking as the rest of the wort. All of that sweet goodness would have been lost w/o a sparge.

If the volume of sparge used was originally integrated into the mash, the gravity retained in the grain as absorption loss would be lower. The mathematical efficiency difference is roughly 3-4%. If that grain cost is worth the sparge effort, cool.

 

[Miraculix]

But not if you squeezed. You're not going to see a material difference if you sparge or if you squeeze.

Exactly. So first squeeze and then sparge afterwards.

 

[mongoose33]

Exactly. So first squeeze and then sparge afterwards.

That would be redundant.

 

[Miraculix]

That would be redundant.

Touch the grain after squeezing. Is it still wet? Yes. Does this still contain wort? Yes. Do you get more out of it with a dunk sparge and a stir and an additional squeeze afterwards? You surely do.

This gets you 2 to 10 percent of additional efficiency, based on the thickness of your mash and the power that went into the first squeeze.

If it is worth the effort for yourself or not is another question but it is certainly not redundant.

 

[JohnSand]

Sometimes you feel like a nut, sometimes you don't.

 

[mongoose33]

Touch the grain after squeezing. Is it still wet? Yes. Does this still contain wort? Yes. Do you get more out of it with a dunk sparge and a stir and an additional squeeze afterwards? You surely do.

This gets you 2 to 10 percent of additional efficiency, based on the thickness of your mash and the power that went into the first squeeze.

If it is worth the effort for yourself or not is another question but it is certainly not redundant.

That really wasn't what we found. The question we had was whether squeezing to get the remaining wort out was equivalent to sparging. Our conclusion was that...it is.

Sparging does not remove all the wort; it rinses, but some still remains. If you were doing a fly sparge, maybe, but you still leave sugar behind even when sparging.

 

[Miraculix]

That really wasn't what we found. The question we had was whether squeezing to get the remaining wort out was equivalent to sparging. Our conclusion was that...it is.

Sparging does not remove all the wort; it rinses, but some still remains. If you were doing a fly sparge, maybe, but you still leave sugar behind even when sparging.

Yes. And doing first a squeeze and then a dunk sparge plus a squeeze again gets even more out.

 

[mongoose33]

Yes. And doing first a squeeze and then a dunk sparge plus a squeeze again gets even more out.

Perhaps...and for what? A theoretical quarter point of gravity? Is it worth it? Kind of defeats the purpose of BIAB, seems to me.

 

[Miraculix]

Perhaps...and for what? A theoretical quarter point of gravity? Is it worth it? Kind of defeats the purpose of BIAB, seems to me.

Please read my previous posts again, they are answering this question.

 

[mongoose33]

Please read my previous posts again, they are answering this question.

And, of course, you should read mine, which also answer it. There is virtually no difference between a good hard squeeze, and sparging. Sparging is just more involved.

 

[Miraculix]

And, of course, you should read mine, which also answer it. There is virtually no difference between a good hard squeeze, and sparging. Sparging is just more involved.

I have never said any different. Again, please read my posts.

 

[whiskeyjack]

BIAB with a sparge is great for when you don't have a pot big enough to do a full volume mash. For instance if you can get 1/2 or 3/4 of the full volume then you can do a pour over sparge or a dunk sparge which sort of appears what you are doing. Bottom line is it doesn't matter how you got there, as long as you hit your numbers it will be beer

 

[kevin58]

@Vintage Iron : Are you mashing in that plastic container? If so may I suggest you get an insulated cooler. It will help you maintain your mash temp a lot better. But yeah, it looks like you are doing it as well as can be expected using a turkey fryer.

 

[Vintage Iron]

@Vintage Iron : Are you mashing in that plastic container? If so may I suggest you get an insulated cooler. It will help you maintain your mash temp a lot better. But yeah, it looks like you are doing it as well as can be expected using a turkey fryer.

No, I'm mashing in the boil pot. I wrap the boil pot in a welding blanket when it gets up to temp. Seemed to hold temp pretty decent. After an hour, I pulled the grain bag and set it on top of the grate above the kettle, first letting it drip, then sqeezing it with the lid of the kettle against the grate.

After that, the bag goes into the plastic container where about 1.5 gal of 170deg water is slowly poured over it. Then it sits for 10 min. The water that was in this container looked "almost" as dark as the wort, so I gotta think a squeeze and then a rinse helped it. (shrug)

I think at that point I may have dumped the sparge water into the kettle, then resqueezed the grains again just so it wasn't a soppy mess. If nothing else, the "don't squeeze your grains" guys from previous years are probably rolling over in their graves! LOL

 

[wilserbrewer]

Sparging PROPERLY DONE always gets you more of the sugars for fermenting and thus improves efficiency.
2. Sparging PROPERLY DONE always gets more of the sugars from the grain. It also adds another step so you have to decide if it is worthwhile of if it would be easier to just buy more grain.
.

FTFY sorry if I’m nitpicking, but a poorly conducted sparge can actually decrease efficiency...or a hastily conducted pour over sparge may not affect efficiency at all, but may help to adjust wort volume.

But yes, in theory I agree, sparging will always increase efficiency.
Whether the increase is worth the effort is debatable.

 

[doug293cz]

@Morrey and I did some work with this--the idea was that squeezing was analogous to sparging in that you're wringing out the residual wort, either mechanically by squeezing or by rinsing (sparging).

We didn't see there as being much if any difference, so do what feels good.

So it sounds like the consensus is that there is no consensus on sparge vs no sparge. I think I'll keep doing it because I was amazed at how much "wort" came off the grain during the sparge. That extra 1.5 gal of water was just as dark looking as the rest of the wort. All of that sweet goodness would have been lost w/o a sparge.

But not if you squeezed. You're not going to see a material difference if you sparge or if you squeeze.

If the volume of sparge used was originally integrated into the mash, the gravity retained in the grain as absorption loss would be lower. The mathematical efficiency difference is roughly 3-4%. If that grain cost is worth the sparge effort, cool.

Exactly. So first squeeze and then sparge afterwards.

That would be redundant.

Touch the grain after squeezing. Is it still wet? Yes. Does this still contain wort? Yes. Do you get more out of it with a dunk sparge and a stir and an additional squeeze afterwards? You surely do.

This gets you 2 to 10 percent of additional efficiency, based on the thickness of your mash and the power that went into the first squeeze.

If it is worth the effort for yourself or not is another question but it is certainly not redundant.

That really wasn't what we found. The question we had was whether squeezing to get the remaining wort out was equivalent to sparging. Our conclusion was that...it is.

Sparging does not remove all the wort; it rinses, but some still remains. If you were doing a fly sparge, maybe, but you still leave sugar behind even when sparging.

Yes. And doing first a squeeze and then a dunk sparge plus a squeeze again gets even more out.

Perhaps...and for what? A theoretical quarter point of gravity? Is it worth it? Kind of defeats the purpose of BIAB, seems to me.

And, of course, you should read mine, which also answer it. There is virtually no difference between a good hard squeeze, and sparging. Sparging is just more involved.

The effects of sparging vs. squeezing vs. doing both when batch (or no) sparging have been calculated based on simple dilution theory by many folks, including me. I have put together a chart that shows how they all fit together.

The assumptions are as follows:

1. Conversion of starch to sugar has stopped (either by achieving 100% conversion, or doing a mash out) prior to any wort being run off.
2. Wort in the mash vessel has been completely homogenized prior to each run off step (initial and sparge.)
3. The grain absorption rate (squeezing level) is the same after every run off step.

The chart plots lauter efficiency vs. the ratio of grain weight (in lbs) to the pre-boil volume (in gal), as this makes the chart independent of batch size. If your conversion efficiency is 100% then mash efficiency will equal lauter efficiency. If conversion is less than 100%, then mash efficiency will be proportionately lower than lauter efficiency. For sparges, each sparge volume is the same as the first runnings volume, until the grain bill increase causes the mash thickness to reach 0.9 qt/lb, at which point strike water remains constant and the sparge water is divided equally among all sparge steps. The calculations for the chart are for the case of 0 undrainable volume in the mash vessel (typical for BIAB.) The solid lines represent the case of no squeezing, which in a typical MLT results in a grain absorption rate of close to 0.12 gal/lb. The dashed lines represent the case of squeezing down to a grain absorption rate of 0.06 gal/lb, typical of a moderately aggressive BIAB squeeze. A BIAB bag applies a slight squeeze on it's own, without any additional action by the brewer, and depending on drain time may give a grain absorption rate of 0.10 - 0.11 gal/lb.

Let's look at what the calculations tell us about a case with a 6.5 gal pre-boil volume and an 11 lb grain bill (ratio = 11 lb / 6.5 gal = 1.7 lb/gal)

Case 1: No Sparge, No Squeeze - Grain absorption = 0.12 gal/lb. The RED circle shows this point on the chart. Lauter efficiency is: 76.9%, and the pre-boil SG is: 1.045 (not on chart, but from spreadsheet.)

Case 2: No Sparge, Squeezed - Grain absorption = 0.06 gal/lb. The BLACK circle shows this point on the chart. Lauter efficiency is: 83.4%, and the pre-boil SG is: 1.049.

Case 3: 1 Sparge, No Squeeze - Grain absorption = 0.12 gal/lb. The GREEN circle shows this point on the chart. Lauter efficiency is: 85.9%, and the pre-boil SG is: 1.050.

Case 4: 1 Sparge, Squeezed - Grain absorption = 0.06 gal/lb. The BLUE circle shows this point on the chart. Lauter efficiency is: 91.9%, and the pre-boil SG is: 1.054.

If we look at Case 3 vs. Case 1, and Case 4 vs. Case 2, sparging always beats no sparging for the same level of squeezing (grain absorption rate.) For "normal" size beers the difference is in the 8.5 - 9.0% range.

If we look at Case 2 vs. Case 3, there isn't a big difference between sparging and not squeezing vs, squeezing and not sparging (especially if we look at SG.) Squeezing harder will improve the efficiency of no sparge, and better draining without squeezing will increase the efficiency of the sparged case.

The case of squeezing and then sparging is always the highest efficiency option.

Now that you have a feel for the quantitative differences among the spage/squeeze options, you can decide for yourself on the effort vs. efficiency trade offs.

All that said, having a consistent process, that allows you to predict what a recipe will produce on your system, is more important to good brewing than a few percentage points of mash/lauter efficiency.

Brew on

 

[Miraculix]

The effects of sparging vs. squeezing vs. doing both when batch (or no) sparging have been calculated based on simple dilution theory by many folks, including me. I have put together a chart that shows how they all fit together.

The assumptions are as follows:

1. Conversion of starch to sugar has stopped (either by achieving 100% conversion, or doing a mash out) prior to any wort being run off.
2. Wort in the mash vessel has been completely homogenized prior to each run off step (initial and sparge.)
3. The grain absorption rate (squeezing level) is the same after every run off step.

The chart plots lauter efficiency vs. the ratio of grain weight (in lbs) to the pre-boil volume (in gal), as this makes the chart independent of batch size. If your conversion efficiency is 100% then mash efficiency will equal lauter efficiency. If conversion is less than 100%, then mash efficiency will be proportionately lower than lauter efficiency. For sparges, each sparge volume is the same as the first runnings volume, until the grain bill increase causes the mash thickness to reach 0.9 qt/lb, at which point strike water remains constant and the sparge water is divided equally among all sparge steps. The calculations for the chart are for the case of 0 undrainable volume in the mash vessel (typical for BIAB.) The solid lines represent the case of no squeezing, which in a typical MLT results in a grain absorption rate of close to 0.12 gal/lb. The dashed lines represent the case of squeezing down to a grain absorption rate of 0.06 gal/lb, typical of a moderately aggressive BIAB squeeze. A BIAB bag applies a slight squeeze on it's own, without any additional action by the brewer, and depending on drain time may give a grain absorption rate of 0.10 - 0.11 gal/lb.

View attachment 567498

Let's look at what the calculations tell us about a case with a 6.5 gal pre-boil volume and an 11 lb grain bill (ratio = 11 lb / 6.5 gal = 1.7 lb/gal)

Case 1: No Sparge, No Squeeze - Grain absorption = 0.12 gal/lb. The RED circle shows this point on the chart. Lauter efficiency is: 76.9%, and the pre-boil SG is: 1.045 (not on chart, but from spreadsheet.)

Case 2: No Sparge, Squeezed - Grain absorption = 0.06 gal/lb. The BLACK circle shows this point on the chart. Lauter efficiency is: 83.4%, and the pre-boil SG is: 1.049.

Case 3: 1 Sparge, No Squeeze - Grain absorption = 0.12 gal/lb. The GREEN circle shows this point on the chart. Lauter efficiency is: 85.9%, and the pre-boil SG is: 1.050.

Case 4: 1 Sparge, Squeezed - Grain absorption = 0.06 gal/lb. The BLUE circle shows this point on the chart. Lauter efficiency is: 91.9%, and the pre-boil SG is: 1.054.

If we look at Case 3 vs. Case 1, and Case 4 vs. Case 2, sparging always beats no sparging for the same level of squeezing (grain absorption rate.) For "normal" size beers the difference is in the 8.5 - 9.0% range.

If we look at Case 2 vs. Case 3, there isn't a big difference between sparging and not squeezing vs, squeezing and not sparging (especially if we look at SG.) Squeezing harder will improve the efficiency of no sparge, and better draining without squeezing will increase the efficiency of the sparged case.

The case of squeezing and then sparging is always the highest efficiency option.

Now that you have a feel for the quantitative differences among the spage/squeeze options, you can decide for yourself on the effort vs. efficiency trade offs.

All that said, having a consistent process, that allows you to predict what a recipe will produce on your system, is more important to good brewing than a few percentage points of mash/lauter efficiency.

Brew on

Omg

Wow I am glad that sometimes people like to be a bit to precise

Thanks for this investigation.

Only one thing I would like to add, as I happen to do a half volume biab yesterday (was a pain), the lower the mash volume compared to final volume, the higher the lauter efficiency will impact the final brewhouse efficiency.

In my case, by the factor two, compared to full volume biab. In other words, the lower the mash volume compared to final volume, the more one profits from adding sparge and squeezes.

 

[Sadu]

Perhaps...and for what? A theoretical quarter point of gravity? Is it worth it? Kind of defeats the purpose of BIAB, seems to me.

A full volume BIAB also raises your mash pH meaning you need to use more acid to get into the correct range for your recipe. For something like a pilsner which already needs a good hit of acidulated malt, I'll usually sparge to keep the acid use reasonable. Not something that beginners need to care about but something to be mindful of later on.

My experience is that with a fine crush I can get good efficiency with sparge or no sparge. I hate squeezing the bag so I just hang it over the boil kettle for the first half of the boil.

 

[doug293cz]

Omg

Wow I am glad that sometimes people like to be a bit to precise

Thanks for this investigation.

I went to the trouble of learning all the math, and creating my own spreadsheet, that describes the processes of mashing and lautering in order to increase my own understanding of the factors that affect the processes. I found the effort to be very rewarding, and my understanding increased immensely. The references I depended on the most are:

http://braukaiser.com/wiki/index.php?title=Batch_Sparging_Analysis
http://braukaiser.com/wiki/index.php?title=Understanding_Efficiency​

You are correct that the theoretical calculations are "too precise" compared to what we can achieve in practice, given the uncertainties in grain potential, grain moisture content, and measurement errors in grain weights, SG's, and volumes. Any efficiency we calculate from our measurements is going to have an accuracy of about +/- 3 to 4 percentage points.

So, if you get 78% mash efficiency one time, and 80% another, you can't really say that they are different. However, differences of about 5 percentage points or greater are probably real.

Only one thing I would like to add, as I happen to do a half volume biab yesterday (was a pain), the lower the mash volume compared to final volume, the higher the lauter efficiency will impact the final brewhouse efficiency.

In my case, by the factor two, compared to full volume biab. In other words, the lower the mash volume compared to final volume, the more one profits from adding sparge and squeezes.

I find your wording a little confusing, but I think the point you are making is that for a fixed set of equipment losses for any particular brew system, the equipment losses have a larger negative effect on efficiency the smaller the batch size. The two places this comes into play are mash vessel undrainable volume, which affects lauter and thus mash efficiency, and brew kettle losses (the difference between fermenter volume and post-boil volume) which affect brewhouse efficiency.

You could also be talking about adding top-up water after the mash or after the boil. For our previous example of 11 lb of grain and 6.5 gal pre-boil volume (1.7 lb/gal), if you did a squeezed no-sparge that resulted in only 3.25 gal of wort that you topped up to 6.5 gal in the BK, then your grain to wort ratio goes from 1.7 to 3.4 (move right on the chart.) So, instead of a lauter efficiency of 83.4% you would only get about 71.5%.

For the case of topping off in the fermenter rather than the BK let's assume that boil off rate with 6.5 gal pre-boil is 0.75 gal/hr and BK to fermenter losses are 0.25 gal, and with 3.25 gal pre-boil the boil off rate is reduced to 0.5 gal/hr, but you lose the same 0.25 gal going to the fermenter. In the first case, your post-boil volume is 5.75 gal, and the fermenter volume is 5.5 gal. Your transfer efficiency is then 5.5/5.75 = 95.7%, and your brewhouse efficiency is 0.957 * mash efficiency. In the second case, your post-boil volume is 2.75 gal, and the fermenter volume is 2.5 gal. In this case your transfer efficiency is 2.5/2.75 = 90.9%, and brewhouse efficiency is 0.909 * mash efficiency.

So, we end up with three possible cases:

Case 1: Full Volume Mash, No Top Up: Brewhouse efficiency = 83.4% * 0.957 = 79.8%
Case 2: Half Volume Mash, Top Up in BK: Brewhouse efficiency = 71.5% * 0.957 = 68,4%
Case 3: Half Volume Mash, Top Up in Fermenter: Brewhouse efficiency = 71.5% * 0.909 = 65.0%​

Larger volumes left behind in the BK will increase the differences between the three cases.

Brew on

 

[Miraculix]

I went to the trouble of learning all the math, and creating my own spreadsheet, that describes the processes of mashing and lautering in order to increase my own understanding of the factors that affect the processes. I found the effort to be very rewarding, and my understanding increased immensely. The references I depended on the most are:

http://braukaiser.com/wiki/index.php?title=Batch_Sparging_Analysis
http://braukaiser.com/wiki/index.php?title=Understanding_Efficiency​

You are correct that the theoretical calculations are "too precise" compared to what we can achieve in practice, given the uncertainties in grain potential, grain moisture content, and measurement errors in grain weights, SG's, and volumes. Any efficiency we calculate from our measurements is going to have an accuracy of about +/- 3 to 4 percentage points.

So, if you get 78% mash efficiency one time, and 80% another, you can't really say that they are different. However, differences of about 5 percentage points or greater are probably real.


I find your wording a little confusing, but I think the point you are making is that for a fixed set of equipment losses for any particular brew system, the equipment losses have a larger negative effect on efficiency the smaller the batch size. The two places this comes into play are mash vessel undrainable volume, which affects lauter and thus mash efficiency, and brew kettle losses (the difference between fermenter volume and post-boil volume) which affect brewhouse efficiency.

You could also be talking about adding top-up water after the mash or after the boil. For our previous example of 11 lb of grain and 6.5 gal pre-boil volume (1.7 lb/gal), if you did a squeezed no-sparge that resulted in only 3.25 gal of wort that you topped up to 6.5 gal in the BK, then your grain to wort ratio goes from 1.7 to 3.4 (move right on the chart.) So, instead of a lauter efficiency of 83.4% you would only get about 71.5%.

For the case of topping off in the fermenter rather than the BK let's assume that boil off rate with 6.5 gal pre-boil is 0.75 gal/hr and BK to fermenter losses are 0.25 gal, and with 3.25 gal pre-boil the boil off rate is reduced to 0.5 gal/hr, but you lose the same 0.25 gal going to the fermenter. In the first case, your post-boil volume is 5.75 gal, and the fermenter volume is 5.5 gal. Your transfer efficiency is then 5.5/5.75 = 95.7%, and your brewhouse efficiency is 0.957 * mash efficiency. In the second case, your post-boil volume is 2.75 gal, and the fermenter volume is 2.5 gal. In this case your transfer efficiency is 2.5/2.75 = 90.9%, and brewhouse efficiency is 0.909 * mash efficiency.

So, we end up with three possible cases:

Case 1: Full Volume Mash, No Top Up: Brewhouse efficiency = 83.4% * 0.957 = 79.8%
Case 2: Half Volume Mash, Top Up in BK: Brewhouse efficiency = 71.5% * 0.957 = 68,4%
Case 3: Half Volume Mash, Top Up in Fermenter: Brewhouse efficiency = 71.5% * 0.909 = 65.0%​

Larger volumes left behind in the BK will increase the differences between the three cases.

Brew on

I think you might have over complicated a bit what I meant.

In a simple way, let's just assume that 20% of the wort is absorbed by the grain doing a full volume biab batch ( I know I know, depends on many factors, it is just assumed to be constant for this explanation).

Therefore all this sparging and squeezing would be about getting those 20% of the solution out of the grain.

For a full volume biab, this would mean that 20% of the wort and sugar are absorbed in the grain.

If you would do the same batch as a half volume biab, already 40 % of the wort would be absorbed by the grain, therefore it would be more rewarding to try to get as much out of the grain as possible.

 

[doug293cz]

I think you might have over complicated a bit what I meant.

In a simple way, let's just assume that 20% of the wort is absorbed by the grain doing a full volume biab batch ( I know I know, depends on many factors, it is just assumed to be constant for this explanation).

Therefore all this sparging and squeezing would be about getting those 20% of the solution out of the grain.

For a full volume biab, this would mean that 20% of the wort and sugar are absorbed in the grain.

If you would do the same batch as a half volume biab, already 40 % of the wort would be absorbed by the grain, therefore it would be more rewarding to try to get as much out of the grain as possible.

That's basically case 1 and case 2 in my immediately preceding post.

Brew on