First high gravity BIAB - tips?

[EnglishAndy]

I'm doing my first high gravity BIAB brew next week and am looking for tips that'll help me to hit my target OG of 1.090.

I normally do 6 gallon brews in the 1.042 to 1.050 range and hit 80-85% BH efficiency. I crush my own grain with a 32 mil gap. I save back about 1.5 gallons for a 10 minute soak-the-bag sparge and I squeeze like it owes me money (which it does).

My 1.090 RIS will be a shorter brew length of 3 gallons and if I follow the usual procedure then I'll be mashing about 10lb of grain in 3.7 gallons of water and then doing my usual 1.5 gallon sparge before boiling for 60 minutes.

I've downgraded my recipe efficiency expectation from 80% to 75% already. Does this sound reasonable? What are your experiences with high gravity BIAB?

 

[doug293cz]

I'm doing my first high gravity BIAB brew next week and am looking for tips that'll help me to hit my target OG of 1.090.

I normally do 6 gallon brews in the 1.042 to 1.050 range and hit 80-85% BH efficiency. I crush my own grain with a 32 mil gap. I save back about 1.5 gallons for a 10 minute soak-the-bag sparge and I squeeze like it owes me money (which it does).

My 1.090 RIS will be a shorter brew length of 3 gallons and if I follow the usual procedure then I'll be mashing about 10lb of grain in 3.7 gallons of water and then doing my usual 1.5 gallon sparge before boiling for 60 minutes.

I've downgraded my recipe efficiency expectation from 80% to 75% already. Does this sound reasonable? What are your experiences with high gravity BIAB?

Your goal of 1.090 OG is achievable. Assuming 3.0 gal is your target to fermenter, how much volume do you typically leave behind in the BK. Do you happen to know what your typical conversion (not mash) efficiency is?

Brew on

 

[EnglishAndy]

Your goal of 1.090 OG is achievable. Assuming 3.0 gal is your target to fermenter, how much volume do you typically leave behind in the BK. Do you happen to know what your typical conversion (not mash) efficiency is?

It's good to hear that what I'm doing is going to be possible. I normally leave about 2 quarts behind in the kettle and, looking back at my Beersmith records my last mash efficiencies have been 83%, 85%, 90%, 87%. I haven't come across conversion efficiency before and I don't see it in Beersmith. Can I calculate it from my other numbers?

 

[doug293cz]

It's good to hear that what I'm doing is going to be possible. I normally leave about 2 quarts behind in the kettle and, looking back at my Beersmith records my last mash efficiencies have been 83%, 85%, 90%, 87%. I haven't come across conversion efficiency before and I don't see it in Beersmith. Can I calculate it from my other numbers?

Mash Efficiency = Conversion Efficiency * Lauter Efficiency
BrewHouse Efficiency = Mash Efficiency * Fermenter Volume / Post-Boil Volume

You can calculate your conversion efficiency using the method here. Lauter efficiency can be calculated from your strike volume, sparge volume, grain bill size and grain absorption rate. I have a spreadsheet here that can do all the calculations. You need to download a copy to use locally in either Excel or LibreOffice Calc, if you want to be able to make it do any of the tricks that involve "Goal Seek." You can calculate your conversion efficiency by having goal seek adjust the conversion efficiency so that the calculated pre-boil SG matches your actual pre-boil SG.

Now for the bad news. With 0.5 gal left in the BK, your transfer efficiency is only 100% * 3.0 gal / 3.5 gal = 85.7%. If I throw that into my previous calculations, you can get a max SG of 1.089, and only if your conversion efficiency is 100%. To get 1.090 or over, you would need to boil off more, and leave less volume behind in your BK.

Brew on

 

[EnglishAndy]

Mash Efficiency = Conversion Efficiency * Lauter Efficiency
BrewHouse Efficiency = Mash Efficiency * Fermenter Volume / Post-Boil Volume

You can calculate your conversion efficiency using the method here. Lauter efficiency can be calculated from your strike volume, sparge volume, grain bill size and grain absorption rate. I have a spreadsheet here that can do all the calculations. You need to download a copy to use locally in either Excel or LibreOffice Calc, if you want to be able to make it do any of the tricks that involve "Goal Seek." You can calculate your conversion efficiency by having goal seek adjust the conversion efficiency so that the calculated pre-boil SG matches your actual pre-boil SG.

Now for the bad news. With 0.5 gal left in the BK, your transfer efficiency is only 100% * 3.0 gal / 3.5 gal = 85.7%. If I throw that into my previous calculations, you can get a max SG of 1.089, and only if your conversion efficiency is 100%. To get 1.090 or over, you would need to boil off more, and leave less volume behind in your BK.

Thanks very much for the spreadsheet. I downloaded it and entered the values from my Beersmith recipe then adjusted the conversion efficiency value so that the spreadsheet's mash efficiency matched what Beersmith was predicting.

The spreadsheet predicts an SG of 1.083 and Beersmith predicts 1.090. Do you know what would account for the difference? Beersmith has always been accurate to within a point or two for me.

[edit] I don't mind tipping the entire kettle into the fermenter if it helps. The brulosophy experiment showed that it doesn't matter and it all packs down in the end anyway.

 

[doug293cz]

BeerSmith doesn't adjust lauter efficiency (or mash efficiency) to account for the larger grain bills for big beers (lauter efficiency goes down and the grain bill gets bigger, all else equal.) My spreadsheet does account for the size of the grain bill. BeerSmith uses the transfer losses (volume left behind in BK, plumbing, etc.) you specify in your equipment profile and batch volume to calculate the transfer efficiency. Then it calculates your estimated mash efficiency as:

Mash Efficiency = BrewHouse Efficiency / Transfer Efficiency.​

Since you specify your estimated brewhouse efficiency, you indirectly specify the estimated mash efficiency as well. It's up to you to adjust your brewhouse efficiency in order for BeerSmith to adjust your estimated mash efficiency.

Brew on

 

[EnglishAndy]

BeerSmith doesn't adjust lauter efficiency (or mash efficiency) to account for the larger grain bills for big beers (lauter efficiency goes down and the grain bill gets bigger, all else equal.) My spreadsheet does account for the size of the grain bill. BeerSmith uses the transfer losses (volume left behind in BK, plumbing, etc.) you specify in your equipment profile and batch volume to calculate the transfer efficiency. Then it calculates your estimated mash efficiency as:

Mash Efficiency = BrewHouse Efficiency / Transfer Efficiency.​

Since you specify your estimated brewhouse efficiency, you indirectly specify the estimated mash efficiency as well. It's up to you to adjust your brewhouse efficiency in order for BeerSmith to adjust your estimated mash efficiency.

I see, I had no idea what adjusting the estimated BH efficiency in Beersmith did behind the scenes.

What I've done now is bring down my estimated efficiency from 75% (which was already reduced from my usual 80% on lower gravity brews) to 70% and have increased boil time to 90 mins so I've got more liquor for the sparge. Beersmith and the spreadsheet are now close enough that it doesn't matter.

Brewday is next Sunday. I'll report back with the numbers attained. Thank you again for the spreadsheet. It's been a valuable preparation tool!

 

[Oldskewl]

FWIW, I usually average around 80% effiency on 1.055-065 brews BIAB. A few months ago I planned to brew a stout with an OG of 1.108. I used 67% in my calculations and ended up with an OG of 1.104. This was a 5 gal batch.

 

[EnglishAndy]

I brewed it today and was very happy with the outcome. I planned for 70% BH efficiency and actually achieved 77%, so only a 5% drop on what I normally get.

Mash efficiency was estimated at 71.5% by Beersmith but I actually got 82% with a pre-boil gravity of 1.070, 5 points higher than the estimate. This boost helped me later because I boiled off about a litre/hour less than I normally do with lower gravity worts. No idea why. Is this normal with thicker worts?

At the end of the day I got 13 litres into the fermenter (1 more than estimated) at a gravity of 1.088. I'm happy with that and I'm quietly confident that the Wyeast 1728 will attenuate more than Beersmith thinks it will.

Thanks a million for the advice Doug, your spreadsheet definitely helped me hit the numbers.

 

[mj1angier]

One thing I have to take in consideration for boil off rate is the humidity. Here in the Southern US the humidity run very high so boil off is less. I have Beersmith set up with two equipment profiles- one for high humidity (summer) and one for low(winter). Its not perfect but it does help.

 

[RM-MN]

I'm doing my first high gravity BIAB brew next week and am looking for tips that'll help me to hit my target OG of 1.090.

I normally do 6 gallon brews in the 1.042 to 1.050 range and hit 80-85% BH efficiency. I crush my own grain with a 32 mil gap. I save back about 1.5 gallons for a 10 minute soak-the-bag sparge and I squeeze like it owes me money (which it does).

My 1.090 RIS will be a shorter brew length of 3 gallons and if I follow the usual procedure then I'll be mashing about 10lb of grain in 3.7 gallons of water and then doing my usual 1.5 gallon sparge before boiling for 60 minutes.

I've downgraded my recipe efficiency expectation from 80% to 75% already. Does this sound reasonable? What are your experiences with high gravity BIAB?

It doesn't take 10 minutes to rinse the sugars off the grain. Pull the bag, squeeze it out, use half the water for the first soak but only long enough to stir the water into the grain. Pull the bag and squeeze it again, then do a final dunk in the rest of the water before pulling the bag out for a final squeeze. This emulates a double batch sparge that would be done with a conventional mash tun.

 

[wepeeler]

FWIW, I usually average around 80% effiency on 1.055-065 brews BIAB. A few months ago I planned to brew a stout with an OG of 1.108. I used 67% in my calculations and ended up with an OG of 1.104. This was a 5 gal batch.

I usually get around 72-75% efficiency on anything up to 1.065. I did a RIS last Thursday (my first "big" beer) using the same 72%, and I ended up only getting around 58% efficiency. Was hoping for a 1.090 and I got 1.080. Didn't realize that efficiency suffers with a bigger grain bill. Always learning!

 

[doug293cz]

I usually get around 72-75% efficiency on anything up to 1.065. I did a RIS last Thursday (my first "big" beer) using the same 72%, and I ended up only getting around 58% efficiency. Was hoping for a 1.090 and I got 1.080. Didn't realize that efficiency suffers with a bigger grain bill. Always learning!

Yep. With more grain you lose more (a larger percentage) of your wort to gain absorption, so in particular, your lauter efficiency decreases.

Brew on

 

[wepeeler]

Yep. With more grain you lose more (a larger percentage) of your wort to gain absorption, so in particular, your lauter efficiency decreases.

Brew on

Seems like the consensus is no sparge with BIAB, but I might try it out. Seems like it's helped people here to squeeze (no pun intended) a few more points.

 

[doug293cz]

Seems like the consensus is no sparge with BIAB, but I might try it out. Seems like it's helped people here to squeeze (no pun intended) a few more points.

"Classic" BIAB is no-sparge, but many folks do sparge with BIAB. For equal grain absorption rates, an equal run-off volumes sparge will give about 8 percentage points better lauter efficiency than no-sparge. Squeezing reduces the grain absorption rate, which also increases the lauter efficiency. The lower the grain absorption rate, the higher the lauter efficiency. The chart below shows how this works.

Brew on

 

[LittleRiver]

...Squeezing reduces the grain absorption rate...

Which squeeze is that?

Is it a squeeze on a freshly hoisted bag, where a significant amount of liquid can be produced? Or is it on a bag that has been allowed to fully drain by gravity, to the point that it is no longer dripping at all?

Technically speaking, in either case if any liquid (even one drop) can be produced it is true to say that the grain absorption rate has been reduced.

But practically speaking, I say that squeezing the fully drained bag will have a negligible impact. So small that it is not worth the effort.

 

[doug293cz]

Which squeeze is that?

Is it a squeeze on a freshly hoisted bag, where a significant amount of liquid can be produced? Or is it on a bag that has been allowed to fully drain by gravity, to the point that it is no longer dripping at all?

Technically speaking, in either case if any liquid (even one drop) can be produced it is true to say that the grain absorption rate has been reduced.

But practically speaking, I say that squeezing the fully drained bag will have a negligible impact. So small that it is not worth the effort.

Yes the longer you drain the bag, the lower the grain absorption will be. Just how much wort can be squeezed out of a bag that has "dripped dry" would need to be tested by experimentation. And the results will depend on just how hard you can squeeze. Whether squeezing is worth it or not is something that each brewer must decide for themselves, based on their process and time constraints.

Brew on

 

[LittleRiver]

... Just how much wort can be squeezed out of a bag that has "dripped dry" would need to be tested by experimentation. And the results will depend on just how hard you can squeeze...

Next time I brew I'll squeeze a fully drained bag, measure the liquid, and post the methods/results here. That will be one data point.

 

[LittleRiver]

One thing I have to take in consideration for boil off rate is the humidity. Here in the Southern US the humidity run very high so boil off is less. I have Beersmith set up with two equipment profiles- one for high humidity (summer) and one for low(winter). Its not perfect but it does help.

What is the difference in the boil off rate of your summer vs winter profiles? I need to do something similar.

 

[mj1angier]

For my 10 gal pot, it runs about 2% more loss in winter. But that will be different for other pots or humidity in your area. I just run a batch of same kind of beer in winter and then in summer and plug in the numbers to beersmith and make a winter profile and a summer one.

 

[MerlinWerks]

I always post THIS when this particular question comes up. It's helped me when trying to get north of 1.070, which isn't very often. Bottom line, do a longer boil so you can use more liquor in the mash/sparge to get all the sugars out of the larger grain bill.

 

[kevin58]

I tried making a 1.103 barleywine recently and experienced the declining efficiency problem explained in the article that @MerlinWerks posted. I didn't reach my goal on that one but after doing some more research I came up with this solution... a partigyle. I did a 10 gallon batch and used the first runnings for the barleywine. My gravity going into the fermenter was 1.104.

You might also want to use a yeast that tolerates a high alcohol environment... Use yeast nutrient in both your starter and in the boil kettle... Aerate well and consider aerating a second time about 12 hours after pitching... And use temperature control during fermentation.

Good luck.

 

[Tribe Fan]

Great thread, very helpful. Thanks!

 

[LittleRiver]

...Just how much wort can be squeezed out of a bag that has "dripped dry" would need to be tested by experimentation...

Doug I have a data point for you. I brewed an oatmeal stout this morning, 5gal batch, 11lb grain bill including 1lb flaked oats and 8oz of flaked barley. I let it drip into the kettle for the entire one hour boil, when I took it off it was still dripping a little. I squeezed it firmly against the inside of a 5 gal bucket, keeping the bottom of the bag off the bucket bottom so liquid would not be re-absorbed. I got 200ml of wort from the squeeze.

The bag seemed to drip for longer/slower than on other brews, I think the flaked oats and barley may have contributed to a slower drain(?). Next time I brew something with a simpler grain bill I'll see if the results are any different, and post here.

 

[doug293cz]

Doug I have a data point for you. I brewed an oatmeal stout this morning, 5gal batch, 11lb grain bill including 1lb flaked oats and 8oz of flaked barley. I let it drip into the kettle for the entire one hour boil, when I took it off it was still dripping a little. I squeezed it firmly against the inside of a 5 gal bucket, keeping the bottom of the bag off the bucket bottom so liquid would not be re-absorbed. I got 200ml of wort from the squeeze.

The bag seemed to drip for longer/slower than on other brews, I think the flaked oats and barley may have contributed to a slower drain(?). Next time I brew something with a simpler grain bill I'll see if the results are any different, and post here.

The 200ml extra wort works out to a difference of 0.005 gal/lb in absorption rate. At a nominal 0.10 gal/lb rate, 0.005 represents an additional 5%. If your rate was more like 0.07 gal/lb, then 0.005 is an additional 7%. Not a huge gain in either case.

Brew on

 

[wilserbrewer]

Very interesting....but from this we can not deduce squeezing produces more wort in total. One can’t assume squeezing after draining and just squeezing are the same.

Try the reverse....squeeze then let drip / drain....likely get another 200 ml?

More so as grain bill increases...imo

 

[doug293cz]

Very interesting....but from this we can not deduce squeezing produces more wort in total. One can’t assume squeezing after draining and just squeezing are the same.

Try the reverse....squeeze then let drip / drain....likely get another 200 ml?

More so as grain bill increases...imo

Agree that doing a complete set of experiments requires many more trials, and keeping track of drain times, squeeze pressure, and probably some more variables.

What I can say is that if you are going to do a dunk (batch) sparge, and don't want to wait for a long drain, squeezing before sparging will give you improved lauter efficiency.

Would be interesting to look at an effectively infinite drain vs. squeezes at various pressures for shorter times.

Brew on