BIAB Water Displacement by Grain

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cotillion

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Hello again, all

As I continue to pore over numerous threads regarding BIAB process, more and more questions pop up. One to which I can't seem to find an answer is in regard to water displacement volumes.

Here is my situation: I have an 8.75 gallon kettle and want to do 5-5.5 gallon batches using BIAB. Do I have room for a typical AG full boil here? I have tried using the rackers calculator, but I can't tell exactly how to interpret it. Does it assume that I will top off the wort once I am finished mashing? How much strike water should I have initially and how do I know how much volume will be displaced by, say, 14 lbs of grain? If I do need to mash and then add more water later, when do I do that and how does it affect my gravity? What wort thickness should I am for with BIAB? I just have no idea how much water to start with and what to expect as the process continues.

Also, in order to increase final alcohol levels, could one simply at beet candy sugar or dextrose or something like that? I know it may be frowned upon as not fully AG, but does it make a major practical difference?

Sorry for that barrage but man, I feel like this stuff can be pretty dense, especially after a couple hours of reading multiple tabs on my screen lol.
 
I like to dunk sparge into two gallons of water for 10 minutes. I've got a 7.5 gallon kettle, and have done a 12 pound mash using this technique. My efficiencies have been in the 75-80% range.
This isn't the true BIAB technique, but I've found it works well for me.
 
Looked fairly good to me.

Try using 10% of your fermenter volume for trub loss

Make a guess for you evaporation, and next time you will have a better value to use.
 
You can do a full mash with all your water, but 14 lbs is pushing it.

Based on some experience and using ez_water_2.0 I find my mash thickness. Generally, I start with 7.5 gallons of water for 11 - 14 lb of grain. I plug in 7.5 gal for mash water and 0.0 gal for sparge water and total grain weight to get my mash thickness.

7.5 gal plus your 14 lbs comes to 2.14 qt/lb which is fine. Now using the GB packers 'can i mash it' I find it will take up 8.61 gallons of volume. That's too close for comfort for me, but do you get the idea?

You can try an 11.5 lb grain bill at a 2.14 qt/lb to see how you like it. I wouldn't go with a mash below a 2.00 qt/lb, personally. Rules are made to be broken though, my last batch was 18 lb and I didn't consider the mash thickness, it was thick and I pulled off a 1.077 OG, but my efficiency suffered.
 
Interesting stuff - thanks for the replies.

I'm not so worried about fitting in with the definition of BIAB, as long as I can find the least complicated way to make a wide range of good 5 gallon batches.

1MadScientist, what is your kettle size? I think I am starting to understand it a little...maybe not, though. So at the given 14 lbs of grain, if I started with 7 gallons of strike water, that would be at 2qts/lb thickness and 8.12 gallons of volume taken up. I'd be left with about .5 gallons of space left, which could be dangerous for boilovers. Is it doable? Am I grasping the concept at all?

What happens to the beer if I start a little thicker for mash and then topped up a bit with some lightly sparged runnings after dunking in a side pot?
 
It's a 15.5 gal converted keg you see in my link at the bottom.

Yep, I think you got it there. It looks like you ran those new numbers. You also have grain absorption when you pull the bag so it will be lower.

Full volume BIAB means you can squeeze the bag for all its worth to get all the juice. If you end up doing a sparge than probably not.

If you what to push the envelope than I highly recommend the product called foam control (FermCapS). You will NOT have boil overs!
 
I use an 8.5 gallon kettle and have done about 10 BIAB batches with it. Grain bills have been from 10-13 lbs. There has always been room for at least another couple of lbs in the pot.

I start with approx 6 gallons of water. I measure inaccurately with a britta charcoal filter pitcher. 6 pitchers to start.

After the mash I pull the bag, place it in a plastic 5 gallon bucket and pour 2 gallons of 195 degree water over it.

That liquid added to the boil pot nets about 6.5 gallons of wort preboil. Its tight and you have to watch the boil. I generally bottle between 52-57 12 oz bottles with this process.

My last batch was a SMaSh with 12 lb of Marris Otter. I got a post boil gravity of 1.062
 
cotillion said:
Interesting stuff - thanks for the replies.

I'm not so worried about fitting in with the definition of BIAB, as long as I can find the least complicated way to make a wide range of good 5 gallon batches.

1MadScientist, what is your kettle size? I think I am starting to understand it a little...maybe not, though. So at the given 14 lbs of grain, if I started with 7 gallons of strike water, that would be at 2qts/lb thickness and 8.12 gallons of volume taken up. I'd be left with about .5 gallons of space left, which could be dangerous for boilovers. Is it doable? Am I grasping the concept at all?

What happens to the beer if I start a little thicker for mash and then topped up a bit with some lightly sparged runnings after dunking in a side pot?
Click to expand...

Looks like you are on the right track. 8.12 gallons will be the volume with all your grain in there though. Once you take it out and start the boil you will probably have around 7 gallons or wort. If you have a 8.75 gallon kettle you shouldn't have to worry to much about boil overs. I have an 8 gallon kettle and start my boils with a volume of 6.8 gallons based on my boil off rate.
 
you can mash with lower water:grain ratios as well

i usually mash at 1.25-1.5 qt/lb and hit 70% efficiency - i've mashed over 16#s of grain in a 30qt kettle before - I use a 2nd vessel for dunk sparging though - i usually adjust the sparge volume based on how much water i need to bring me to my boil volume

you can fill your kettle as full as you want while mashing - it won't be a risk of boil over because you will remove your grain before boiling, but it can make it harder to move or place the lid on if it's too full

it will prob take a few batches for you to figure out your proper volumes - everyone's will vary based on evaporation, trub/hop absorption etc

you shouldn't have any issues with boil overs in a 8.75gal BK unless your flame is really raging
 
Here's what I do:

1.) Calculate my mash water volume with this calculator, and since I do basic BIAB with all my water in the kettle with the grains I adjust the mash thickness so that 'Total Water Needed' and 'Mash Water Needed' are equal, and 'Sparge Water Needed'=0. Take note of your mash thickness and...

2.) Enter mash thickness and weight of grains into the 'Can I Mash It?' calculator from this page.

For example, take the default entries in the first calculator, 5 gallons, 10 lb grain, total water 8.67 gallons. Adjust the mash thickness to make mash water and total water about equal -- I get 3.46 qt/lb.

So, in the second calculator enter your grain weight, 10 lb, and your mash thickness, 3.46 qt/lb, hit calculate, and you get "This mash will take up 9.45 gallons of space."

Piece of cake, just note that the calculator does not take into account any false bottoms, strainers, or other space-taking contraptions you might have in your kettle.
 
Oh, and also, the first calculator can be adjusted for your system. Since we do BIAB, we can adjust the absorption rate. I usually set it at .08, some would say .07, some would say .10. Whatever works for you. And with my system, equipment loss and trub loss are only .25 gallons each, so that's where I set those.
 
cotillion said:
Hello again, all

As I continue to pore over numerous threads regarding BIAB process, more and more questions pop up. One to which I can't seem to find an answer is in regard to water displacement volumes.

Here is my situation: I have an 8.75 gallon kettle and want to do 5-5.5 gallon batches using BIAB. Do I have room for a typical AG full boil here? I have tried using the rackers calculator, but I can't tell exactly how to interpret it. Does it assume that I will top off the wort once I am finished mashing? How much strike water should I have initially and how do I know how much volume will be displaced by, say, 14 lbs of grain? If I do need to mash and then add more water later, when do I do that and how does it affect my gravity? What wort thickness should I am for with BIAB? I just have no idea how much water to start with and what to expect as the process continues.

Also, in order to increase final alcohol levels, could one simply at beet candy sugar or dextrose or something like that? I know it may be frowned upon as not fully AG, but does it make a major practical difference?

Sorry for that barrage but man, I feel like this stuff can be pretty dense, especially after a couple hours of reading multiple tabs on my screen lol.
Click to expand...

Hi there mate.

As Rifester said, biabrewer.info is the best resource for all things BIAB, especially since it was started and is being run by the people that started the whole thing.

There is a simple calculator on the biabrewer website that helps a lot with your beer, but there is another one in development that is significantly better.

For wort thickness, I don't really worry about that, the thickness is just whatever it is. I always get great conversion and extraction efficiency using BIAB.

To increase gravity and fermentability, you can use beet sugar, candi sugar, dextrose or even normal granulated sugar. This will in turn increase the final ABV % if your yeast can handle it.
I won't recommend adding more than approximately 10% of these sugars.

If you want good advice on all volumes, the BIABrewer forum is very active, so I would recommend you look for assistance there for BIAB volumes.

Good luck! :)
 
Ok. Used that. Said 18.63 gal for 36 lbs grain. Does that mean it will not overflow when i add it to the water?
 
People usually calculate all the volumes needed based on losses from grain absorption, trub etc. Just to get you started and keep it simple I went through my last couple brew spreadsheets and calculated the total biab volume/into fermentor volume = 1.62. So whatever you want in your fermentor multiply that volume by 1.62. That's on my keggle system, but it should get you close I think.
 
owentp said:
16 gal batch, 18 total water volume in 20.5 gal pot, 35 lbs grain. Will I overflow?
Click to expand...

I figure 18 gal or 72 qt / 35 lb = 2.06 qt / lb

Rackers calc tells me 20.83 gallons mash volume meaning to me you will have several pound of grain on the floor!

I would mash with a few gallons less, and max out your kettle with boiling water after the hour mash.

If needed you could also sprinkle sparge a gallon over / through the grain bag to reach preboil volume.
 

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