# BIAB High Gravity

I honestly don’t brew a lot of high gravity beers, but as a loyal BIAB’er, I do find I have a lower mash efficiency with higher gravity beers. I typically do 2q/pound of grain for mash thickness and crush fine. I have noticed significantly lower efficiency with beers over 1.070.

Anyone have any thoughts or similar experience?

Same here, but I’m doing a modified BIAB where I use a similar water ratio to traditional 3-vessel all grain. Bag o’ grain goes in the cooler with 1.2-1.5 qt water per pound grain, heat sparge water in kettle, and after an hour take the bag out of the cooler and dunk it in the sparge water.

The last time I used 1.25 qt/# and had more sparge water, and I got about 80% efficiency on a higher gravity beer. I know it’s not pure BIAB, but adding the sparge with a higher amount of water really got the efficiency back.

This isn’t necessarily a BIAB problem… although it often is because people don’t bother to sparge when doing BIAB. But I do.

If you sparge, I find that regardless of whether you BIAB or batch sparge, gravity points plus efficiency is almost a constant. For example, if you normally brew 1.060 beers and get 75% efficiency, your constant will be 60 + 75 = 135. Using this value of 135, you can back calculate on any other recipe of X specific gravity to determine the anticipated efficiency. So for the same brewer with a constant of 135, if they want to brew something of original gravity of 1.080, they’ll know that their efficiency will be closer to 135 - 80 = 55%. This is a little conservative and they’ll probably actually get closer to 60%, but my point is that there is a very real balance between the two things.

If the same brewer is getting 60 + 75 = 135 but doing BIAB without sparge, the effects might be more dramatic, since a sparge would help. Maybe they really will only get 55% for that 1.080 beer. So even a simple dunk of the grain bag in hot water for a couple of minutes might be all that’s needed to bring efficiency up another 5 to 10 percentage points.

That’s why I sparge, even though I BIAB about 95% of the time. The only time I don’t sparge is when brewing something less than 1.045, where it really just doesn’t matter because my efficiency hits 90% or more without even trying.

Crush hard, and sparge well, and you will be very happy.

Wow thats a helpful calculation, thanks Dave! That all makes sense.

I typically do a 2 gallon sparge in a spare ale pail with 170* water.

Yep, it works slick. Take a look at the last 5 batches you’ve done. Add together your efficiency and your gravity points for each batch, then take the average to figure out your own personal constant. I bet it’s somewhere between 130 and 145. Then use that constant from now on with your desired OG for any new recipe to figure out your estimated efficiency and tweak your grain bill with that efficiency in mind BEFORE you brew. Voila, problem solved.

:cheers:

That is brilliant Dave!
I just went back to my spreadsheet and added them up- by gosh you’re right. I use a Denny-style 5G cooler with a braid for most of my batches and I’m very consistent there. However I’ve been experimenting with a hybrid BIAB-in-a-large-cooler for large grain batches(over 13 lbs). My numbers there are definitely lower but I’m still working out the process.

[quote=“dmtaylo2”]Yep, it works slick. Take a look at the last 5 batches you’ve done. Add together your efficiency and your gravity points for each batch, then take the average to figure out your own personal constant. I bet it’s somewhere between 130 and 145. Then use that constant from now on with your desired OG for any new recipe to figure out your estimated efficiency and tweak your grain bill with that efficiency in mind BEFORE you brew. Voila, problem solved.

:cheers: [/quote]

One caveat to this: This calculation works for biab and single batch sparge. I brew often on my friend’s 1/2 bbl system and we recirc the mash and fly sparge, and we usually get around 80% mash efficiency even on a few big beers we have done (1.090 RIS, 1.078ish IIPA)

Yes, sir, you are correct, sir.