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First brew completed! - efficiency/water issues!

Hello, I did my first BIAB yesterday and am getting a little confused about the water quantity. I ended up with what looks like a 62.3% efficiency.

I wanted to make a 20L batch

I had a recipe which said I needed 25.88L in the boil to be left with 21.88 for fermentation. I mashed with 24L and intended to sparge with 7 based on the predicted 15% boil off rate.

I have ended up with 23.5L in my fermentation pot (planned for 21.9). I actually got just over 5% for the boil rate so had more water than planned, Because of this I only sparged with 5L in the end instead of the 7 I’d put on the recipe.

This was still too much as I’m way over. The recipe from brewfather says to get these volumes with the 15% boil off I had, I need this water, but it didn’t work out like that on the day!

Anyone able to point out what I’m doing wrong?

Please let me know if more information is needed


Yes you are adding to much water. Don’t go by what the recipe says use your volume in your kettle to determine top up water. When you do BIAB you aren’t doing a sparge jus adding water. After you drain your bag just add enough water to get to the preboil volume you want. It doesn’t matter if your a little under just add water at the end of the boil.

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Also remember the grains won’t retain more water so if you want 22L and you collect 20L you add 2L. You don’t need to do water calculator for BIAB unless you do a full volume mash

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Thank you, this has helped so much!

Ill do the recipe again, Mash with like 20L and then I can just top up to the pre-boil volume!

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I don’t worry about final volume until I put the wort in the fermenter. That’s when I bring it up to volume. Adding clean water at the very end help cool down the wort for pitch yeast as well. I casually follow the following math. Bring up 5 gallons to temperature, soak my grains, drain my BIAB, sparge with 1 gallon, make the wort, strain and drain into fermenter, top off fermenter. There are so many variable in there that will change how much wort goes into the fermenter (ie amount of hops). So i always aim to be under.

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It was mostly trial and error for me. I discovered that 7.75 gallons of water is the sweet spot for most of the 5 gallon biab recipes that I do using around 12 to 15 lbs of grain.

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This is not fermenting, all seems well however my temperature is fluctuating from 64 to 69 depending on time of day. Is this likely to cause a big problem?

This is now fermenting*

So just a trip… Get it up to about 70* now for a week… :mask:

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