Trying to understand all grain batch sparging

[Yooper]

See, the above exchange is where I was thrown.. I didn't see any temps mentioned for the ".6 addition" and already had the understanding that the quote below held true...




And to throw more about mash temps into the mix for a new PM / AG brewer...

Mash temps do matter...

http://www.howtobrew.com/section3/chapter14-1.html

Yes of course mash temps matter! But we're talking about sparging here.

 

[AnOldUR]

No, that's a "mash out" addition.

Like she says above, it's not really a mash out if you don't raise the bed temperature to denaturing levels. Think of it as simply topping off the mash. It allows you to use a mash thickness that won't let pH get out of hand, but still do no-sparge or to balance out your volume so that you get equal runnings if you are batch sparging. The top off addition is not technically sparging since no wort has left the tun before this point.

 

[joshesmusica]

I heat my total water volume in the brew kettle, then add to the mash tun(s). After mash, I drain those in collection buckets which allows me to (1) measure the strength of each "running" (2) decide if 2 batches sparges are fine or if I want to do a third (3) keep the strike water separate and heat it during mash so its essentially at mash out temps, and have control in case I mess up numbers and need to add more or not use as much.

When I have collected my total volume of wort (usually two batch sparges), I can dump any excess strike / sparge water and add the collected worts to the kettle.

I used to do two sparges, collect in buckets, and then do a dunk sparge with the mash (in paint strainer bags) inside the kettle with the remaining water. Often that dunk water would be ~1.020. On my last batch, I had too much grain for one cooler, but it was only 1/2 capacity for two coolers. I did two batch sparges where I added mashout water just before I drained it making the qt/lb ratio very soupy. My efficiency went from my typical 80% up to 87%. I didn't do a dunk sparge this time and felt like I had really good control.

If this is confusing, please ask for clarification. I found it really easy, and forgiving. Sometimes I find the trickiest part is estimating your initial total water volume.

The problem with this method is that the enzymes continue to work while you're waiting to start up the boil. I would bet you're getting pretty low attenuation out of the beers mashed this way. Unless you're mashing at really high temps to make up or this?

 

[masonsjax]

Mashing modern grains is done very quickly. Many of us have been doing 15-20 min mashes with very little change in fermentability. If a 60 min mash doesn't thin out your beer, taking a few mins to get to a boil certainly wont hurt.

 

[pudland]

Yes of course mash temps matter! But we're talking about sparging here.

Yes yes...! Sorry, off topic! My bad...

 

[AnOldUR]

Mashing modern grains is done very quickly. Many of us have been doing 15-20 min mashes with very little change in fermentability. If a 60 min mash doesn't thin out your beer, taking a few mins to get to a boil certainly wont hurt.

That has less to do with modern grains and more to do with technique. "Many of us" are not using the fine crush and BIAB that's needed for the 15 minute mash to be effective.

 

[masonsjax]

I've been doing 20 min mash for a couple of years now using my cooler w/braid mash tun. It works great and shaves a bunch of time off a brew day. I don't want to derail this thread, but the point is that skipping a mashout will not appreciably impact wort fermentability.

 

[pudland]

I'm really interested in batch sparge to save time on brew day, so maybe this is the way to go?

So... with the plethora of info... how have you decided to proceed?

 

[joshesmusica]

I've been doing 20 min mash for a couple of years now using my cooler w/braid mash tun. It works great and shaves a bunch of time off a brew day. I don't want to derail this thread, but the point is that skipping a mashout will not appreciably impact wort fermentability.

Have you done any side by side comparisons of the same recipe mashed at 20 and at 60 mins, as it pertains to flavor, mouthfeel, aroma, head retention, etc.?

 

[broadbill]

Have you done any side by side comparisons of the same recipe mashed at 20 and at 60 mins, as it pertains to flavor, mouthfeel, aroma, head retention, etc.?

check out RM-MN's posts on the subject, on this forum.

 

[broadbill]

The problem with this method is that the enzymes continue to work while you're waiting to start up the boil. I would bet you're getting pretty low attenuation out of the beers mashed this way. Unless you're mashing at really high temps to make up or this?

you mean high attenuation....if enzymes continue to convert then they are producing more fermentable sugars and you get increased attenuation.

 

[AnOldUR]

I've been doing 20 min mash for a couple of years now using my cooler w/braid mash tun. It works great and shaves a bunch of time off a brew day. I don't want to derail this thread, but the point is that skipping a mashout will not appreciably impact wort fermentability.

What's the mash temperature? Step mash? No-sparge or multiples? Heat runnings as soon as there's enough in kettle or wait until full volume is collected? How much time from when you start your lauter and the wort reaches denaturing temperatures? All these things and more vary greatly from brewer to brewer. How much a mashout will change the fermentabiliy of the wort depends on the answers and can have an appreciable impact on it.

 

[joshesmusica]

you mean high attenuation....if enzymes continue to convert then they are producing more fermentable sugars and you get increased attenuation.

Yeah I meant it attenuates to a lower gravity.

 

[doug293cz]

...

Taken from Dennybrew:
Let’s see how this works in a brewing session. Assume a recipe with 10 lb. of grain, and that you need to collect 7 gal. of pre boil wort. A mash ration of 1.25 qt./lb. would require 12.5 qt. or 3.125 gal. of strike water. Based on an absorption of .1 gal./lb., the mash would absorb 1 gal. of water so we’d get 2.125 gal. of water from the mash. Since we want to collect 3.5 gal. (or 50% of the boil volume), after the mash is complete we’d add 1.375 gal. (5.5 qt.) of water to mash tun before the first runoff. Stir the additional water in, let it sit for a few minutes, then vorlauf until clear and start your runoff. After the runoff, we add 3.5 gal. of batch sparge water. Stir it in well, then vorlauf and runoff as before. These two runoffs will give us our pre boil volume of 7 gal. of sweet wort.

The "Dennybrew Method" is based on maximizing efficiency based on two assumptions:

1. That a strike water to grain ratio near 1.25 qt/lb will maximize conversion efficiency, and
2. That equal run off volumes will maximize lauter efficiency when batch sparging.

So, you mash at the chosen strike water to grain ratio (to maximize conversion efficiency), and then before initial run off you add enough additional water so that you will get equal run off with your sparge(s).

The problem is that the first assumption has been proven wrong by Kai Troester (http://www.braukaiser.com/wiki/index.php?title=Understanding_Efficiency). Quoting Kai:

"In the limit of attenuation experiments it was shown that a 5 l/kg (2.4 qt/lb) mash showed much better conversion efficiency than a 2.5 l/kg (1.2 qt/lb) mash. This is also supported by anecdotal experience from home brewers who found that thin mashes generally lead to better overall efficiency.

While thick mashes help to stabilize the enzymes which makes them active for a longer time, they also inhibit their activity (substrate inhibition) and make it more difficult for the starch to gelatenize. As a result in thinner mashes the conversion processes occur faster. "​

So, since thinner mashes do not decrease conversion efficiency (if anything they improve it), there is no benefit to limiting the strike water to grain ratio to low values. You will be better off mashing in with all of the water needed to achieve the initial run off volume. You do need to make sure your water adjustments are based on the larger strike volume to insure correct mash pH.

The second assumption upon which the "Dennybrew Method" is based is valid. It is based on well established rinse dilution mathematics.

Note: The incorrect assumption that thicker mashes provide faster conversion than thinner mashes is based on a simplistic and flawed analysis that considers enzyme concentration as the only parameter important in controlling saccharification rate (at a particular temperature.) As Kai points out a higher concentration of starches and dextrines works to inhibit the action of the enzymes, and is actually a more important factor than the enzyme concentration.

Brew on

 

[Denny]

hi guys, just finished up making my mash tun and hlt, getting ready to do my first all grain brew. I'm confused about some of it. I do have beersmith and friends who do all grain, but they fly sparge with a pretty complicated system. So from what I gather...
I'll mash in with whatever amount and temp beersmith provides me after pre heating the mash tun. This part seems easy enough. Now where I'm confused is on batch sparging.

At the end of 60 min mash, I should add the first small amount of Sparge water, then stir, Let sit 10 mins, vorlauf, Drain completely.

Then add second larger addition of sparge water, stir, let sit 10 mins, vorlauf, then drain. Is this all correct? Seems like I wouldn't be rinsing all the sugars off with all the stirring.

I'm also confused on why I need hotter sparge water.

No, you don't add a small amount of sparge water and let it sit. There is never any need to let the sparge water sit before runoff.

You use hotter sparge water to insure you have complete conversion before running off your sparge. Many people think they're doing a mashout but they're not. Almost no homebrewer raises the grain bed above 170 and lets it sot for 20 min., which is what you need to do for a mashout. In additon, beciaseu you get t a boil so much more quickly when you batch sparge compared to fly sparging, there is no benefit to doing a mashout. see www.dennybrew.com for complete ionfo.

 

[Denny]

I do this exactly. It is how Denny does it, and it works.


Taken from Dennybrew:
Let’s see how this works in a brewing session. Assume a recipe with 10 lb. of grain, and that you need to collect 7 gal. of pre boil wort. A mash ration of 1.25 qt./lb. would require 12.5 qt. or 3.125 gal. of strike water. Based on an absorption of .1 gal./lb., the mash would absorb 1 gal. of water so we’d get 2.125 gal. of water from the mash. Since we want to collect 3.5 gal. (or 50% of the boil volume), after the mash is complete we’d add 1.375 gal. (5.5 qt.) of water to mash tun before the first runoff. Stir the additional water in, let it sit for a few minutes, then vorlauf until clear and start your runoff. After the runoff, we add 3.5 gal. of batch sparge water. Stir it in well, then vorlauf and runoff as before. These two runoffs will give us our pre boil volume of 7 gal. of sweet wort.

I no longer recommend that method. Increase the amount of mash water so you get approximately 1/2 your total boil volume from the mash. Get the rest of your boil volume from the sparge.

 

[Denny]

Also, what is the reasoning for wanting both "runnings" of the batch sparge to be the same amount of water? Not sure I understand that either.

It's not the same amount of water...it's the same amount of wort run off. You need to use more water for the mash due to grain absorption. Theoretically, you get the highest efficiency that way. But in reality as long as the mash and sparge runoff are within about a gal. of each other it's pleanty close enough!

 

[joshesmusica]

The "Dennybrew Method" is based on maximizing efficiency based on two assumptions:

1. That a strike water to grain ratio near 1.25 qt/lb will maximize conversion efficiency, and
   
2. That equal run off volumes will maximize lauter efficiency when batch sparging.

So, you mash at the chosen strike water to grain ratio (to maximize conversion efficiency), and then before initial run off you add enough additional water so that you will get equal run off with your sparge(s).



The problem is that the first assumption has been proven wrong by Kai Troester (http://www.braukaiser.com/wiki/index.php?title=Understanding_Efficiency). Quoting Kai:

"In the limit of attenuation experiments it was shown that a 5 l/kg (2.4 qt/lb) mash showed much better conversion efficiency than a 2.5 l/kg (1.2 qt/lb) mash. This is also supported by anecdotal experience from home brewers who found that thin mashes generally lead to better overall efficiency.



While thick mashes help to stabilize the enzymes which makes them active for a longer time, they also inhibit their activity (substrate inhibition) and make it more difficult for the starch to gelatenize. As a result in thinner mashes the conversion processes occur faster. "​

So, since thinner mashes do not decrease conversion efficiency (if anything they improve it), there is no benefit to limiting the strike water to grain ratio to low values. You will be better off mashing in with all of the water needed to achieve the initial run off volume. You do need to make sure your water adjustments are based on the larger strike volume to insure correct mash pH.



The second assumption upon which the "Dennybrew Method" is based is valid. It is based on well established rinse dilution mathematics.



Note: The incorrect assumption that thicker mashes provide faster conversion than thinner mashes is based on a simplistic and flawed analysis that considers enzyme concentration as the only parameter important in controlling saccharification rate (at a particular temperature.) As Kai points out a higher concentration of starches and dextrines works to inhibit the action of the enzymes, and is actually a more important factor than the enzyme concentration.



Brew on

I no longer recommend that method. Increase the amount of mash water so you get approximately 1/2 your total boil volume from the mash. Get the rest of your boil volume from the sparge.

Well there ya go, that about solves that issue.

 

[Denny]

It can be mathematically proven that you get maximum lautering efficiency if each sparge run off is equal volume (ref: http://braukaiser.com/wiki/index.php?title=Batch_Sparging_Analysis.) In order to get equal run offs, divide your target pre-boil volume by the number of run offs you will conduct (1 + the number of sparge steps.) Then add your predicted grain absorption to this number to get your strike water volume. Predicted grain absorption is your total grain weight times the absorption rate for your system (typically 0.11 to 0.125 gal/lb for traditional MLT's.)

Forget about traditional mash water to grain ratios. Those are only appropriate for fly (continuous) sparging. Thinner mashes will help with your efficiency.

Brew on

And equal runoffs just don't make that much difference in reality.

 

[Denny]

Seems that you guys are only sparging once? I've read that there are benefits to adding half the sparge water, stirring, and draining, then repeating with the last portion of sparge water. Or is this just wasting time?

Nope, no benefit. The only reason to do that is if you can't fit all your sparge water in the mash tun at once.

 

[doug293cz]

And equal runoffs just don't make that much difference in reality.

Yes, that's something we should always keep in mind. We don't need to obsess about trying to get the run offs exactly equal. Here's the relevant chart from Kai's sparge simulation work (http://braukaiser.com/wiki/index.php?title=Batch_Sparging_Analysis):



The difference between having two 3.5 gal run offs and one 2.8 gal and one 4.2 gal run off is only about half a percentage point in lauter efficiency.

Note: Kai's chart above is a little pessimistic on actual efficiencies since he assumes a grain absorption of 0.19 gal/lb. Actual lauter efficiencies get significantly better with lower (and more typical) grain absorptions.

Brew on

 

[Denny]

I've seen a few who use Beersmith have wonky volumes- like sparge with .6 gallons in one round and then 3.2 gallons in the next. Well, you can't even stir a mash with only .6 gallons of water in it! If the total sparge volume fits in the MLT and it stirs up easily (stir it like it owes you money!) then one batch sparge is fine.

As great as Beersmith is, it's not instructions about how to brew. It's a tool you use to brew the way you want to.

 

[Yooper]

As great as Beersmith is, it's not instructions about how to brew. It's a tool you use to brew the way you want to.

Yes, that was my point. So many newer brewers say, "Well, Beersmith told me to......."

I really love using Beersmith but it's only as good as the data I put into it. The standard profiles for equipment definitely need to be tweaked for each brewer.

By the way, thanks for weighing in Denny! It's always a pleasure to "see" you.

 

[Denny]

Your comparison is flawed... in the first example you are mashing at 1.63 qrts/lb. In the second it is 1.3 qrts/lb. It's not apples to apples.


Actually it is the opposite. I believe that a thicker mash means more enzymes are in contact with the grain, which leads to a more complete conversion.
Bruakaiser confirms this in a chart:
http://www.braukaiser.com/wiki/index.php?title=Understanding_Efficiency

Not on real life. My efficiency went up 5% due to raising my mash ratio from 1.25 to 1.75.

 

[Denny]

One thing not yet discussed here is the rate at which you should drain your mashtun. John Palmer's online edition of How To Brew says you should shoot for a flow rate of 1qt per minute. If you're putting 7 gallons in the pot, that means nearly 30 minutes of your brew day is spent just draining the mashtun. I've been wondering, do people really adhere to this rate in practice?

John is talking fly sparging, since he doesn't batch sparge. In batch sparging you can run off as quickly as your lauter system will allow.

 

[acidrain]

I no longer recommend that method.

First I've heard of that. I've been quoting your site for some time, and now I'm scratching my head.

Am I off base in thinking that mashing at a "normal" grain to water ratio of around 1.25 to 1.33 qrts per lb., and then "topping up" for the first running (as anOLDUR so eloquently put it), will yield both optimum conversion and equal runnings?

 

[Denny]

Mashing modern grains is done very quickly. Many of us have been doing 15-20 min mashes with very little change in fermentability. If a 60 min mash doesn't thin out your beer, taking a few mins to get to a boil certainly wont hurt.

The idea of homebrewers doing a short mash comes from a misunderstanding of the commercial brewing process. Sure, many commercial breweries only do a 15-20 min. rest. but it takes them maybe an hour to mash in, and over an hour to sparge. All the time they're at mash conversion temps, so their actual time in the conversion range is much longer.

 

[judsonp]

Unfortunately, BeerSmith doesn't currently support making it easy to create a recipe that does sparging in what I think is the easiest way.

There are a bunch of options:

1. The BeerSmith default, which is to mash with a particular water-to-grain ratio, top up with some sparge water, drain the mash tun, and then add water to do a full second sparge. This lets you both mash at a particular water-to-grain ratio and get even runoffs, but I think is unnecessarily complicated. As mentioned, this is the default behavior in the BeerSmith "batch sparge" mash profiles.

2. Just mash with whatever water-to-grain ratio you want, drain the mash tun without adding any water, and then add all of the remaining water to the sparge. This is convenient, but you can end up with very different runoff volumes, depending on your grain bill. If you're really worrying about every efficiency point, maybe that matters to you, but data suggests that it's not a big deal. This isn't the default in BeerSmith, but it's well-supported: in your mash profile, check the box to drain mash tun before sparge and uncheck the box to insist on equal runoff volumes.

3. Like #2, use the simple "mash, drain, sparge once" approach, but instead of using a standard water-to-grain ratio, pick your mash water amount so that you end with equal runoffs. I think this is what Denny suggested above. I like it because it's dead simple. This could be implemented in BeerSmith with a simple checkbox, but currently it isn't (as far as I know).

The complicated way to create #3 is BeerSmith is this:
* Use a standard batch sparge, no mash out profile.
* On the mash page, the sparge instructions will be something like "add 0.62 gal of water, drain mash tun, add 3.75 gal of water, drain mash tun". (I'm paraphrasing because I don't have a copy of the software in front of me right now.)
* Edit the mash profile and increase the amount of mash water to include the first sparge. In the example I gave, that's 0.62 gal.
* Now the instructions should either have that first sparge volume be pretty small or gone entirely.
* Go back to the mash profile. Turn off the checkbox to make runoff volumes equal and turn on the checkbox to drain mash tun before sparging.

Honestly, that's kind of a pain. Once you've done it once, though, you should have a good idea of how much water that is on your system. In the future, you can just eyeball it. You won't get exactly equal runoffs, but they'll be roughly equal, and that's all you're looking for. On my system, for example, I know that I'll use 5 to 5.5 gal of mash water (I have a lot of dead space) and I expect to see about 3.5 gal for the sparge. So I'll just jump right to plugging in 5 gal for the mash volume and check to make sure the sparge volume is in the right ballpark.

Note: You need to be careful with BeerSmith batch sparge volumes if your mash profile is set to make equal runoff volumes. If the runoff from the mash is larger than half the pre-boil volume, by default it will increase the batch sparge volume so that the two runoff volumes are equal. This will result in you getting more wort than your pre-boil volume, which is a problem! Like Yooper said, don't just trust what your software says! An easy way to fix this is to not use mash profiles that insist on equal runoff volumes.

 

[pudland]

Yes, that was my point. So many newer brewers say, "Well, Beersmith told me to......."

I really love using Beersmith but it's only as good as the data I put into it. The standard profiles for equipment definitely need to be tweaked for each brewer.

By the way, thanks for weighing in Denny! It's always a pleasure to "see" you.

I agree... thats why I just found and read these today..
http://www.beersmith.com/forum/index.php/topic,5140.45.html

Read reply 1,2 & 3... and associated files.

They both say the profiles are a "starting point" for new brewers.... Read, read again, and take notes.

Use the info from that thread... combine the info from this thread and after a few brews, with detailed notes, give beersmith the right data to help give you the right(or close to) outcome.

My extract brews were even far off from BS2... because I used default settings without telling it WHAT I ACTUALLY HAVE, equipment wise.

 

[pudland]

This will result in you getting more wort than your pre-boil volume, which is a problem! Like Yooper said, don't just trust what your software says! An easy way to fix this is to not use mash profiles that insist on equal runoff volumes.

I thought i read in here that after anything after the first drain may be unnecessary(if you can mash in up to 1/2 your boil vol, counting in absorbtion). So you could measure first runnings and add sparge vol to make up the difference... or did I misread?

 

[AnOldUR]

Am I off base in thinking that mashing at a "normal" grain to water ratio of around 1.25 to 1.33 qrts per lb., and then "topping up" for the first running (as anOLDUR so eloquently put it), will yield both optimum conversion and equal runnings?

My eloquence was referring to pH not conversion efficiency. :cross:

Think of it as simply topping off the mash. It allows you to use a mash thickness that won't let pH get out of hand, but still do no-sparge or to balance out your volume so that you get equal runnings if you are batch sparging. The top off addition is not technically sparging since no wort has left the tun before this point.

 

[pudland]

So with all the information provided... where has this left the OP?
Still confused?
Playing catch up can be tough..
Is it even possible to take this thread and give him something he can conceive as a starting point in one post for a first time AG brewer?

 

[acidrain]

My eloquence was referring to pH not conversion efficiency. :cross:

True, but that is the first time I've heard it put that way, and not many people understand what I'm even talking about when describing that theory, so I will steal your terminology (probably wrongly) and use it loosely all over the internet.

So with all the information provided... where has this left the OP?
Still confused?
Playing catch up can be tough..
Is it even possible to take this thread and give him something he can conceive as a starting point in one post for a first time AG brewer?

Deep subject for sure.

 

[thespiff]

John is talking fly sparging, since he doesn't batch sparge. In batch sparging you can run off as quickly as your lauter system will allow.

So I thought I misread, but I went back and looked again, and he really doesn't specify fly or batch sparge:
http://www.howtobrew.com/section3/chapter17.html

The wort should be drained slowly to obtain the best extraction. Sparge time varies depending on the amount of grain and the lautering system, .5 - 2.5 hours. Sparging means "to sprinkle" and this explains why you may have seen or heard discussion of "sparge arms" or sprinklers over the grain bed for lautering. There is no reason to fool with such things. There are three main methods of sparging: English, batch and continuous.

Later on he is more explicit and recommends 1qt per minute in the lautering section (http://www.howtobrew.com/section3/chapter17-2.html) but there's no indication that this section is specifically for a fly sparge process.

Anyway I'm pretty psyched to hear that sparging quickly is the way to go, as it will remove at least 20 minutes from my brew day

 

[wilserbrewer]

Yea....that was written in the Stone Age before Denny invented batch sparging

 

[thespiff]

Yea....that was written in the Stone Age before Denny invented batch sparging

Haha I just realized that Denny is Denny Conn. And here I was wondering whether to trust the advice of the random set of internet forum commenters who responded to my question.

 

[ba-brewer]

So with all the information provided... where has this left the OP?
Still confused?
Playing catch up can be tough..
Is it even possible to take this thread and give him something he can conceive as a starting point in one post for a first time AG brewer?

I was wondering the same thing.

@OP, once you get all of this figure out, have at it and take a bunch of note. Then repeat the process a few time as quick as you can and in no time you will be wondering what the big deal is all about.

 

[masonsjax]

The idea of homebrewers doing a short mash comes from a misunderstanding of the commercial brewing process. Sure, many commercial breweries only do a 15-20 min. rest. but it takes them maybe an hour to mash in, and over an hour to sparge. All the time they're at mash conversion temps, so their actual time in the conversion range is much longer.

Hey Denny, I'm all ears when you have something to say. I know you and I have discussed this point a bit in the past already, but I still have to respectfully disagree. I'm not in the habit of performing very scientific experiments or recording data of any kind. I generally take a more artistic approach, but I have been mashing for 15-25 mins rather than my typical 60 mins for the last 50 or so batches with almost zero discernable difference in the finished beer (single infusion / batch sparge). Perhaps I'll start logging my numbers to publish something at some point, but I would recommend everyone at least try it once and see if they think the extra point or two is worth another 30-45 mins of waiting around. It's certainly not worth it to me.

 

[mcfire12]

So... with the plethora of info... how have you decided to proceed?

Well I think I can read my brains out but I won't be able to find my preferred method until I try several different ways. But I guess for my first AG brew i'm pretty much going to do what BS2 tells me to do, well pretty much. my recipe has 8.28 pounds of grain in it. Going to mash in with 2.6 gallons of water at 163* water hoping that drops everything to 152 when I add my grain.

To sparge, beer smith tell me to do it with 2 steps, first with 1.92 gallon, second with 3.51 gallon using 168* water from my HLT. I think i'm just going to add the first 1.92 gallon to the initial mash, vorlauf, drain, and put to heat right away in my bk. And for the second i'll dump in my 3.51, stir, let sit a few mins, vorlauf, then drain. And I think that's pretty much it.

Is this sounding about right?

 

[mcfire12]

The "Dennybrew Method" is based on maximizing efficiency based on two assumptions:

1. That a strike water to grain ratio near 1.25 qt/lb will maximize conversion efficiency, and
2. That equal run off volumes will maximize lauter efficiency when batch sparging.

So, you mash at the chosen strike water to grain ratio (to maximize conversion efficiency), and then before initial run off you add enough additional water so that you will get equal run off with your sparge(s).

The problem is that the first assumption has been proven wrong by Kai Troester (http://www.braukaiser.com/wiki/index.php?title=Understanding_Efficiency). Quoting Kai:

"In the limit of attenuation experiments it was shown that a 5 l/kg (2.4 qt/lb) mash showed much better conversion efficiency than a 2.5 l/kg (1.2 qt/lb) mash. This is also supported by anecdotal experience from home brewers who found that thin mashes generally lead to better overall efficiency.

While thick mashes help to stabilize the enzymes which makes them active for a longer time, they also inhibit their activity (substrate inhibition) and make it more difficult for the starch to gelatenize. As a result in thinner mashes the conversion processes occur faster. "​

So, since thinner mashes do not decrease conversion efficiency (if anything they improve it), there is no benefit to limiting the strike water to grain ratio to low values. You will be better off mashing in with all of the water needed to achieve the initial run off volume. You do need to make sure your water adjustments are based on the larger strike volume to insure correct mash pH.

The second assumption upon which the "Dennybrew Method" is based is valid. It is based on well established rinse dilution mathematics.

Note: The incorrect assumption that thicker mashes provide faster conversion than thinner mashes is based on a simplistic and flawed analysis that considers enzyme concentration as the only parameter important in controlling saccharification rate (at a particular temperature.) As Kai points out a higher concentration of starches and dextrines works to inhibit the action of the enzymes, and is actually a more important factor than the enzyme concentration.

Brew on

So... what you're saying is in my recipe in the above post I just made, that I should add my 1.92 gallon on top of my initial 2.6 gallon of mash water. So for my mash I should be at 4.5 gallon, let it sit 60 mins. And sparge once with my 3.5 gallon of water? I planned on just measuring whatever I get out of the mash tun for my first running, then adding whatever I actually need to achieve my pre boil volume in beer smith which is 6.73 gallons.

Is this about right? Wow, this all grain thing can get pretty confusing!