BIAB questions

I'm getting ready to do a BIAB for a few friends while my brewstand is being complete, and I'd like to hit my numbers as closely as possible.

Does anyone know the volume lost by removing the grain? Obviously it depends on the amount of grain, but does anyone have idea what the ounces of wort lost per pound of grain is? That would help me figure out how much I'll need in my kettle to start out.

Also, I've seen that some people put the grain in a bucket to allow it to drain a little more while they bring their wort to a boil. Does anyone sparge a gallon or so of water through there to help get some of the sugars? It just seems like such a waste.

I do partial mash BIAB and I usually sparge a gallon or so to get most of the way up to my boil volume.

Not sure about actual volume lost, I'm sure there are so many things that factor into that number (crush, mash thickness, # of grain, etc.) that it's probably best to measure it on your system and use that info.

Hello, as far as sparge go's, I BIAB AG batches and do a dunk sparge for 10 min at my second step temp, in a second pot with 2 gallons of water, Im getting much better efficiency using the dunk sparge compared to without.

You can also rinse/pour sparge through the grain with a gallon or 2.

Hope this helps

Cheers

Thanks WileE, that does help. Do you use 170 degree water to dunk?

I do full volume eBIAB, no sparge. I don't loose much water. I have to boil fairly vigorously to get down to my batch size. To quote someone on this forum, I "squeeze the bag like it owes me money". Mashing out at 170 will help with preventing water loss and ideally increasing efficiency.

Google the "simple BIAB calculator" it will do your math for you.

As a note, I usually multiply the pounds of grain by .06 to determine the absorption. This is a pretty standard value. This would mean .72 gal absorbed for 12 pounds of grain.

I also do not sparge. I pull the bag and let it drain after mashing out at 170. Then I place it in a bucket to continue to drain and collect the additional runnings when the boil starts. Then I discard the grains. Usually get 70%+ efficiency this way.

If you dunk sparge you will have to split your water volumes I believe. May make this a bit more complex. Sparge is not really needed if you stir the grist. I stir every 15 during mash and constantly as I raise the temp to 170 for mash out.

Make your sparging easy. Pull the bag and let it drain into the pot. Squeeze out all the wort you can, then look how much wort you have collected and decide how much more you need for your pre-boil. Use hot or cold water of that amount to dunk or pour through the grains, then squeeze all you can out of the bag again. You should be right at your pre-boil.

RM-MN said:

Make your sparging easy. Pull the bag and let it drain into the pot. Squeeze out all the wort you can, then look how much wort you have collected and decide how much more you need for your pre-boil. Use hot or cold water of that amount to dunk or pour through the grains, then squeeze all you can out of the bag again. You should be right at your pre-boil.

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I do this as well and am right on or very near my numbers.

lunchbox said:

Thanks WileE, that does help. Do you use 170 degree water to dunk?

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Yes I do, but I use a strike water temp of about 178 to 186 to end up with a 170 temp, depending on how much grain I am using in a batch, also I divide up my grain bill equally into 3, 5 gallon paint strainer bags, makes it a lot easy'r to handle the grain and I can also get a good stir in each bag during the dunk sparge, most of the time I dunk sparge 2 bags and heat my wort to 170 with 1 bag still in it, then a quick dunk and stir of that 3rd bag in the sparge water.

Using 3 bags has made the biggest difference for me in handling the grain, stirring, weight, draining, moving grain, dunk sparging, squeezing bags, its all a lot easy'r to deal with since I started using 3 bags, especially the dunk sparging.

I use those black spring'y office clips (medium size, about 1 1/2" wide) to hold my bags from falling into the pot, with 3 bags the clips are clamp strong enough to hold the bags out of the wort to let them drain before moving to the dunk sparge, same after the dunk, also squeeze to get my volumes like RM-MN said.

I think 2 bags would work, but I haven't tried that yet, maybe on my next batch Ill try 2 bags.

Cheers and good luck