Another Batch Sparging Question...Sigh

[TBC27]

I recently switched from fly sparging to batch sparging and had a quick question.

Before I jump into the question I want to preface with the fact I am following Denny's batch sparging process where you try and conduct two equal volume runnings that will equal the preboil volume needed.

QUESTION: If a want my starting mash thickness to be 1.5 qts/lb, how should I handle my strike water volume when my total grain weight takes my strike volume OVER half of my pre-boil kettle volume? Do I make my starting mash thickness more thick? Or can I, in this particular scenario where I am brewing a bigger beer, simply use less sparge water and not have two equal volume runnings without compromising my mash efficiency?

Hopefully this makes sense! :rockin:

 

[day_trippr]

You're going to lose a huge amount of strike volume to the grains, so if the strike and sparge volumes are equal what drains out of the MLT will be dramatically different.

I'm not familiar with the method you examined, but if it attempts to provide equal volumes from the first and batch runnings the strike volume would have to be much larger than the sparge...

Cheers!

 

[nikvolkert]

Maybe do a combination of the two...slightly thicker on the mash and a slightly smaller sparge. I've had good results using 1.3 qts/lb before.

 

[TBC27]

nikvolkert & day_trippr - Thank you for your replies. Let me elaborate a bit further by giving a specific example for a quad I am looking at brewing in the near future.

I use brewersfriend for storing my recipes and helping with water volumes, which are based off of an "equipment profile" I set based on my equipment, deadspaces, losses, etc. during my typical brew day.

The grain bill for my quad recipe is:
9 lbs Belgian Pilsner
7 lbs Belgian Pale Ale
2 lbs Dark Belgian Candi Sugar (I did not include this "weight" in my water volume calculations)

Brewersfriend (again, based on my equipment profile) says I will need a total of 9 gallons of water on brew day in order to get 5.5 gallons in my fermentor. It also specifies I need 7.15 gallons of wort in my kettle pre-boil. It is this number, based on Denny's batch sparging process, that I divide by 2 in order to get my "equal volume" runnings/drains from my mashtun. Basic math then tells me 7.15 gallons/2 is 3.575 gallons of wort I should collect after mashing for 60 minutes and then again during sparging.

Now, to return to my original post and question...with my desired mash thickness of 1.5 qts/lb of grain and my total grain bill being 16 lbs, I need to add 6 gallons of strike water. Based on my system and accounting for grain absorption, I can estimate that the wort I will actually collect into my kettle is 4.4 gallons. It is THIS number (4.4 gallons) that is larger/higher than the 3.575 gallon number above, which represents two equal wort drainings (mash & sparge).

Is this a problem? Will it cause my efficiency to decrease? Should I add less strike water volume initially so my two drainings are actually equal, but also causes my mash to be thicker than I ideally want?

Here is Denny's article on this particular batch sparging process. http://hbd.org/cascade/dennybrew/

My head hurts!

 

[eric19312]

with a large grain bill you have a few options

1 - mash at less than 1.5 qt/lb - this probably has minor impact on efficiency
2 - collect more of your kettle volume from first runnings (smaller sparge) which will hurt efficiency
3 - collect more wort and boil longer (start your actual 60 minute boil when kettle reaches 7.15 gal) - this will give you maximum efficiency but could be a long boil

Personally I went with option 1 when I batch sparged. I used mash software (beer alchemy but any of the others would be fine) and adjusted the mash thickness parameter until the first runnings and second runnings were about equal. So long as this kept me above 1.25 qt/lb I did not worry about it at all. When grain bill was so large that this would put me below 1.25 I would hold at 1.25 and then look at option 3 collect more wort and boil longer.

 

[TBC27]

with a large grain bill you have a few options

1 - mash at less than 1.5 qt/lb - this probably has minor impact on efficiency
2 - collect more of your kettle volume from first runnings (smaller sparge) which will hurt efficiency
3 - collect more wort and boil longer (start your actual 60 minute boil when kettle reaches 7.15 gal) - this will give you maximum efficiency but could be a long boil

Personally I went with option 1 when I batch sparged. I used mash software (beer alchemy but any of the others would be fine) and adjusted the mash thickness parameter until the first runnings and second runnings were about equal. So long as this kept me above 1.25 qt/lb I did not worry about it at all. When grain bill was so large that this would put me below 1.25 I would hold at 1.25 and then look at option 3 collect more wort and boil longer.

Thank you! Your options presented make complete sense and I agree that option #1 seems the most feasible. Cheers!

 

[doug293cz]

nikvolkert & day_trippr - Thank you for your replies. Let me elaborate a bit further by giving a specific example for a quad I am looking at brewing in the near future.

I use brewersfriend for storing my recipes and helping with water volumes, which are based off of an "equipment profile" I set based on my equipment, deadspaces, losses, etc. during my typical brew day.

The grain bill for my quad recipe is:
9 lbs Belgian Pilsner
7 lbs Belgian Pale Ale
2 lbs Dark Belgian Candi Sugar (I did not include this "weight" in my water volume calculations)

Brewersfriend (again, based on my equipment profile) says I will need a total of 9 gallons of water on brew day in order to get 5.5 gallons in my fermentor. It also specifies I need 7.15 gallons of wort in my kettle pre-boil. It is this number, based on Denny's batch sparging process, that I divide by 2 in order to get my "equal volume" runnings/drains from my mashtun. Basic math then tells me 7.15 gallons/2 is 3.575 gallons of wort I should collect after mashing for 60 minutes and then again during sparging.

Now, to return to my original post and question...with my desired mash thickness of 1.5 qts/lb of grain and my total grain bill being 16 lbs, I need to add 6 gallons of strike water. Based on my system and accounting for grain absorption, I can estimate that the wort I will actually collect into my kettle is 4.4 gallons. It is THIS number (4.4 gallons) that is larger/higher than the 3.575 gallon number above, which represents two equal wort drainings (mash & sparge).

Is this a problem? Will it cause my efficiency to decrease? Should I add less strike water volume initially so my two drainings are actually equal, but also causes my mash to be thicker than I ideally want?

Here is Denny's article on this particular batch sparging process. http://hbd.org/cascade/dennybrew/

My head hurts!

Based on your 9.0 gal total brewing water and 7.15 gal pre-boil volume, to get equal runnings of 3.575 gal, you would need a strike volume of 5.425 gal. The mash thickness would then be 1.356 qt/lb, which is not unreasonably thick (1.25 qt/lb is commonly used.) The predicted lauter efficiency for equal runnings is 80.42%.

If you stay at a mash thickness of 1.5 qt/lb, then you need 6.0 gal of strike water, and 3.0 gal of sparge water. The predicted lauter efficiency for this case is 80.26%.

As you can see the difference in efficiency between equal runnings, and not quite equal runnings is very small (too small to measure in fact, with the equipment and methods used by homebrewers.)

So, don't sweat it.

Brew on

 

[TBC27]

Based on your 9.0 gal total brewing water and 7.15 gal pre-boil volume, to get equal runnings of 3.575 gal, you would need a strike volume of 5.425 gal. The mash thickness would then be 1.356 qt/lb, which is not unreasonably thick (1.25 qt/lb is commonly used.) The predicted lauter efficiency for equal runnings is 80.42%.

If you stay at a mash thickness of 1.5 qt/lb, then you need 6.0 gal of strike water, and 3.0 gal of sparge water. The predicted lauter efficiency for this case is 80.26%.

As you can see the difference in efficiency between equal runnings, and not quite equal runnings is very small (too small to measure in fact, with the equipment and methods used by homebrewers.)

So, don't sweat it.

Brew on

Interesting! How did you calculate those numbers to determine the negligible difference?

 

[doug293cz]

Interesting! How did you calculate those numbers to determine the negligible difference?

I have a mash/lauter simulator that I wrote based on concepts that Kai Troester describes here.

Edit: I wrote a description of what goes on inside the simulator here.

Brew on

 

[day_trippr]

BOOM! [^drops the microphone^]

 

[TBC27]

I have a mash/lauter simulator that I wrote based on concepts that Kai Troester describes here.

Edit: I wrote a description of what goes on inside the simulator here.

Brew on

Wow! I'm positive I didn't fully consume everything in your first link. However, I did follow the main concepts. As far as takeaways go, your grain absorption ratio jumped out at me. My water volume calculations have been using an absorption ratio of .1 qt/lb of grain versus your number of .19. That's almost double my number! This means I need to use more water, yes?

 

[doug293cz]

Wow! I'm positive I didn't fully consume everything in your first link. However, I did follow the main concepts. As far as takeaways go, your grain absorption ratio jumped out at me. My water volume calculations have been using an absorption ratio of .1 qt/lb of grain versus your number of .19. That's almost double my number! This means I need to use more water, yes?

The 0.19 gal/lb is Kai's estimated value for true grain absorption, which is higher than the apparent grain absorption, which is typically ~ 0.12 gal/lb for a traditional MLT. You want to use apparent grain absorption in your calculations of water volume. I'm not sure why Kai is using true absorption in his calculations/charts, as it isn't necessary, and confuses people. I don't use true absorption in my simulator.

Apparent grain absorption is calculated as follows:

Grain_Abs_Rate [gal/lb] = (Strike_Vol [gal] - (First_Runnings_Vol [gal] + Undrainable_Vol [gal])) / Grain_Weight [lb]​

Brew on