Grain Absorption and water calculations EBIAB

[don_bran321]

I just bought a new pot and wanted to try my hand at BIAB since my 3v system is a pain to assemble and disassemble every brew day. (small condo)

My question is how do you calculate the grain Absorption to figure out how much total water is needed so that when you lift the bag you have proper starting volume?

I typically fly sparge till I get 7.2gal of wort for a 5.5 gallon batch.

I'm looking for the same result but not sure how to account for grain absortion.

Who got me?

 

[Oginme]

So, are you squeezing the bag to get the wort out, just allowing it to drip back into the pot, or not allowing any of the wort which comes with the grains to drain back into the pot? I squeeze pretty well and get 0.16 qts/lb of grain for grain absorption. If I don't squeeze and just allow the wort to drip from the bag until the pot reaches boiling, I get 0.29 qts/lb of grain. If I were to just remove the bag without letting the wort drip back into the pot, then I would be somewhere in teh vicinity of .5 qts/lb of grain in water absorption. YMMV.

It really comes down to making an educated guess, but without knowing how you are managing the process, anyone's else's figures can be way off.

 

[CascadesBrewer]

Note, while you are tuning in your numbers, there is still some flexibility with BIAB. I will pull out my grain bag and let it hang above my kettle to drain. After a few minutes of draining, I will grab a volume and gravity reading. Depending on volume I can either stop when I hit my target, squeeze to get more, or pour over some water for a simple sparge (I keep some jugs of distilled water around). If I am low on gravity, I can gather a little extra water and adjust my boil length or vigor. It is not quite as easy as fly sparging, but not too bad.

After a few batches, I feel like I got my numbers where I get the volume needed with gravity and a gentle squeeze. I dialed my expected efficiency back a few points recently because I felt like I was having to work too hard to hit my target and I would rather just throw in 4 oz more grain.

 

[mirthfuldragon]

My question is how do you calculate the grain Absorption to figure out how much total water is needed so that when you lift the bag you have proper starting volume? [...]I'm looking for the same result but not sure how to account for grain absortion.
Who got me?

www.biabCalculator.com is what I use. The stock value of 0.045 is no-squeeze. I use 0.035 when squeezing and prolonged dripping and that works for me. I note it on my brew log and make small adjustments each batch, and at this point 0.035 works for me.

 

[balrog]

PricelessBrewingCalc
Stock absorption of .08 is close to what mine eventually came in as (.077875) and will get you close.
I raise, drain while heating 12-15m to boil, adding drips collected during that time, no squeeze, no fuss.

 

[don_bran321]

www.biabCalculator.com is what I use. The stock value of 0.045 is no-squeeze. I use 0.035 when squeezing and prolonged dripping and that works for me. I note it on my brew log and make small adjustments each batch, and at this point 0.035 works for me.

Wow. This is easy to use. Thank you

 

[don_bran321]

Thanks everyone. Great feedback per usual

 

[wilserbrewer]

For a 5 gallon batch, typical starting volume is around 7.5 - 8 gallons.
Rather than rack your brain trying to guess at unknowns that you will acquire w experience, go ahead and brew a batch, and make adjustments moving forward.

Of course, larger beers require more water than smaller beers due to grain absorption....

 

[toxdoc49]

I don't want to start a new thread; I was looking for a forum topic that was related as best I could. I came up short from an all grain brew on water volume for a 5 gallon batch, but the OG was on target. It has been in primary fermentation for 24 hours. Should I just let it go? Also, lesson learned about water volume. The grain absorbed more water than I expected.

 

[mirthfuldragon]

I don't want to start a new thread; I was looking for a forum topic that was related as best I could. I came up short from an all grain brew on water volume for a 5 gallon batch, but the OG was on target. It has been in primary fermentation for 24 hours. Should I just let it go? Also, lesson learned about water volume. The grain absorbed more water than I expected.

More important is to note your values for future reference. If your volume is low and your OG is "on target", that means at the anticipated volume, your OG would be low, so your efficiency is lower, and your grain is absorbing more water, or your volume measurements are off. Takes notes, do a "post-mortem" calculations to figure out efficiency, and then you can make adjustments with your next batch to hit all your numbers, or at least get closer. What works for me on my system using my process does not necessarily work for you on your system using your process. It is all part of the learning curve.

Once it hits the fermentor and yeast is pitched, let it ride. RDWHAHB.