I need some help with low BIAB efficiency please

[PsychoBiter]

We did our first BIAB this past Saturday and had pretty low efficiency. I had bumped up the grain bill by 10% in hopes of not getting a low efficiency. I have read about people getting 80-85%, I was hoping for 75%. We got 65%.....so, I need some help on what happened. Was it is a brewing mistake or calculation mistake?

The set up is a keggle with a Wilser bag and a Reflectix insulation for mashing. We shoot for 7.5 gallons at the end of the whole process, keg 5 gallons and bottle the rest. We used RO water with no additives. We have done 4 AG batches previous, but wanted to try BIAB.

We did a porter based off Denny Conn’s recipe, but amped up the grain bill for a 7.5 gallon batch and an additional 10% to help with efficiency.

Here is the grain bill and my estimated potential sugars in the grain. Are these correct? I just used published grain lists and went from there. I had asked the brew shop to double crush the grains, but not sure if that happened or even where their mill is set. We only have the 4 previous all grain brews under our belts, so I really didn’t know what the grain should have looked like.

Grain bill
21.5# 2 row 1.037 795.5 potential points
4.125# Munich Malt 1.033 136.125 pp
2.5# Brown Malt 1.032 80 pp
2.0# Chocolate Malt 1.029 58 pp
1.65# Crystal 120L 1.033 54.45pp
.825 Crystal 40L 1.034 28.05
32.6# total 1152.125 total points

With my calculated volumes for a full volume batch, it came out to be 12.1 gallons of water needed. With 32.6# of grain, my ratio was 1.48 qts/lb. The “Will it mash” site I used said I would need 14.6 gallons of mash tun. It’s a keggle, so it should be 15.5 gallons, but it all wouldn’t fit. We pulled some wort off the bottom, set it to the side to add back into the boil, and dumped the rest of the grains in.

My mash temp was 151 for the whole 75 minute mash, stirring every 20 minutes, it never dropped in temp. No mash out was done because the bag was full and didn’t want to burn it by trying to heat the keggle.

It took some coaxing to get the bag out of the 12” opening of the keggle, but we slowly got it out and let it drain. We did a little squeezing and got to our target preboil volume of 9.75gallons.

With a preboil potential SG @ 100% efficiency of 1.118, we were at 1.071, right at 60%. I wasn’t happy, as I thought I taken the right steps to get a higher efficiency such as stirring, consistent mash temps, added 10% more grain and double crushed grains.

Post 90 minute boil volumes we were right on target at 8.3 gallons, but an SG of 1.089 for about 65% total efficiency.

So what would cause this low efficiency? The only thing I can come up with is the crush, unless I am missing something.

 

[jwalk4]

Apparently, that's just what happens sometimes on high gravity brews.

https://www.homebrewtalk.com/showthread.php?t=228627
https://www.homebrewtalk.com/showthread.php?t=354801
https://www.homebrewtalk.com/showthread.php?t=206408

I'm at work, so no access to software to trouble shoot your recipe.

 

[EJay]

Crush is certainly a place that can yield a few more points (quite a few, in fact). With BIAB there is no stuck sparges, so you can go real tight. I just use a corona mill but you're doing larger grain bills so you might want something bigger. I saw a jump when i went from double-crush at lhbs to crushing at home.

You can get more efficiency still (and would help with your volume problems) by doing what I think of as a 'sponge sparge' - Leave a small amount of water aside, put the grain bag after the mash into a separate container, drain what you can, then saturate it (like getting a sponge wet) with that water you set aside, at mash-temp if you can, squeeze again, and you'll keep rinsing out more sugars up to a point.

I do smaller batches usually and set my bag into another pot with a vegetable steamer on the bottom, and the bag keeps dripping while my boil water heats, and those drippings are sugar-rich.

65 isn't terrible for a first attempt, consistency is more important, but those tips will get you a little more.

 

[wilserbrewer]

A double crush on a loose mill is likely still a somewhat coarse crush.

Google some pics of a proper grain crush where all the kernels are well broken and no whole kernels remain. If you still have your spent grain, take a close look at it for whole kernels...that will tell you something.

 

[Aristotelian]

I get 65% using BIAB too. I've done a few things to tweak my process and nothing seems to work. Now I just use 65% as my target and everything turns out great.

 

[LLBeanJ]

Besides what the previous posters have mentioned, since you're using RO water, you really need to be adding some minerals back to your water in order to keep the mash pH in the zone. If pH is too high or too low, it can affect mash efficiency.

 

[McKnuckle]

The “Will it mash” site I used said I would need 14.6 gallons of mash tun. It’s a keggle, so it should be 15.5 gallons, but it all wouldn’t fit. We pulled some wort off the bottom, set it to the side to add back into the boil, and dumped the rest of the grains in.

Can you elaborate on this? The mash volume prediction should not be wrong. It's mash water + (0.08 x lbs grain), measured in gallons. I get about 14.7 with 12.1 gal of water.

Did you use too much water by accident, which would then be a more dilute mash, and subsequent lower gravity? And if you pulled wort off the bottom - was it at the very beginning, before conversion, such that you added mostly plain water into the boil (more dilution)?

 

[pricelessbrewing]

65% on that big of a brew is not that bad.

For more information, you need more measurements. You need to be able to separate the mash efficiency into conversion and lauter efficiency, which you can read about on my blog. Until you do so, it's all guess work.

Could be a bad dough in, could be a bad crush, could be mash ph, could be not mixing before pull the bag, could be a poor sparge (if you sparged). There's a bunch of reasons why things can go wrong, but without more information, we really can't isolate the variables.

 

[BeardedBrews]

That's a pretty big beer for no-sparge, I'm with the group that says your 65% brew house is pretty good. Are you saying that you added 10% grain over the totals you have listed there, or is that your actual total grain bill?

Based on my calcuations, you were at 80-90% conversion efficiency, depending on what your final mash gravity was. There might be a few points in there that you could have gotten out with a finer crush, but not a ton.

The real losses are happening in the 2.25 gallons of strike water that are still hanging up there in your grain bag. Adding sparge water to rinse some of those sugars out will help your overall efficiency. Since you are already having to reserve a portion of the strike water to fit in the kettle, it might not be that hard to plan for 2-3 gallons of sparge next time.

The people getting in the 80's are talking about running a 1050 beer in a bag. At that point we're in the 2-3qt/pound range with very high mash conversion (95%+), and there's only 12 pounds of grain so it's easy to squeeze more liquid out. For me, I'm happy when I hit 75% brew-house on my 1050 beers.

 

[doug293cz]

I ran the grain bill and pre-boil numbers thru my mash simulator and came up with the following:

Apparent grain absorption rate = 0.072 gal/lb
Conversion Efficiency = ~ 85%
Lauter Efficiency = 70 - 71%
Mash Efficiency = ~ 60% (= Conversion Efficiency * Lauter Efficiency)​

The only ways to increase lauter efficiency are to reduce the grain absorption rate by squeezing more aggressively, or to add a sparge step.

The low hanging fruit is your conversion efficiency. Homebrewers can routinely achieve conversion efficiencies in excess of 95%. The biggest two factors in conversion efficiency are crush coarseness and mash time. The gelatinization step of conversion starts at the surface of the grits and proceeds towards the centers. The larger the grits (the coarser the crush) the longer the gelatinization takes to complete. Saccharification (starch to sugar conversion) cannot occur until the starch is gelatinized. So conversion cannot complete until gelatinization is complete. Thus coarser crushes need longer mash times.

Longer mash times will help, but may not be able to compensate totally for too coarse a crush. The amylase enzymes denature slowly at mash temps, and in a long enough mash with a coarse crush, you have a race going on between completing gelatinization and enzyme denaturing. And sometimes the enzymes lose, so that the conversion will never complete, no matter how long the mash.

Had you achieved 95% conversion in your mash, your efficiency numbers would have looked like this:

Conversion Efficiency = 95%
Lauter Efficiency = 69 - 70%
Mash Efficiency = ~ 66%
Pre-boil SG = 1.078​

And at 100% conversion efficiency, the numbers look like this:

Conversion Efficiency = 100%
Lauter Efficiency = ~ 69%
Mash Efficiency = ~ 69%
Pre-boil SG = 1.081 - 1.082

​

Edit: To give you some idea of how lauter efficiency varies with the size of the grain bill, take a look at the following chart. This chart is for 6.7 gal pre-boil volume, for various different grain absorption rates. The sparge options assume single batch sparge with equal volume runnings. Chart would need to be scaled for your larger pre-boil volume, but the trends would be the same.



Brew on

 

[PsychoBiter]

Thank everyone so much for your input! Here is some more info....

Crush is certainly a place that can yield a few more points (quite a few, in fact). With BIAB there is no stuck sparges, so you can go real tight. I just use a corona mill but you're doing larger grain bills so you might want something bigger. I saw a jump when i went from double-crush at lhbs to crushing at home.

You can get more efficiency still (and would help with your volume problems) by doing what I think of as a 'sponge sparge' - Leave a small amount of water aside, put the grain bag after the mash into a separate container, drain what you can, then saturate it (like getting a sponge wet) with that water you set aside, at mash-temp if you can, squeeze again, and you'll keep rinsing out more sugars up to a point.

I think the crush is maybe a big part of the culprit, I'll hit up the LHBS and see what they can tell me about their mill settings, that may be the "a-ha" moment. We just requested a double crush, not sure what we even got. Sounds like a sparge of some kind is in order as well.

A double crush on a loose mill is likely still a somewhat coarse crush.

Google some pics of a proper grain crush where all the kernels are well broken and no whole kernels remain. If you still have your spent grain, take a close look at it for whole kernels...that will tell you something.

I guess we are at the mercy of the LHBS until we get our own mill.

Besides what the previous posters have mentioned, since you're using RO water, you really need to be adding some minerals back to your water in order to keep the mash pH in the zone. If pH is too high or too low, it can affect mash efficiency.

We don't have a PH meter, I have read that the strips are worthless, especially in a dark beer. Anyway to determine without buying a meter? What would you suggest adding to correct for PH based on our grain bill and using RO water. I do know the RO water typically runs 6.8 on the PH scale, I used my pool tester to estimate.

Can you elaborate on this? The mash volume prediction should not be wrong. It's mash water + (0.08 x lbs grain), measured in gallons. I get about 14.7 with 12.1 gal of water.

Did you use too much water by accident, which would then be a more dilute mash, and subsequent lower gravity? And if you pulled wort off the bottom - was it at the very beginning, before conversion, such that you added mostly plain water into the boil (more dilution)?

I am very confident that we used the right amount of water, the water comes in 3 packs of 1 gallon jugs and we bought 4 to make up our 12 gallons, I added a small portion of a left over one from our last brew to get to 12.1. I need to double check the volume of the keggle I guess. I didn't weigh the grain before either, I just trusted what the LHBS gave me. Not sure how accurate they weigh, but would assume that don't over fill grain bills on a regular basis, or they would be losing money.

The wort/water that we pulled out of the bottom, was very dark and not plain water, but it was part of the total volume I had calculated, so it shouldn't dilute the overall volume going into the pre-boil....?

65% on that big of a brew is not that bad.

For more information, you need more measurements. You need to be able to separate the mash efficiency into conversion and lauter efficiency, which you can read about on my blog. Until you do so, it's all guess work.

Could be a bad dough in, could be a bad crush, could be mash ph, could be not mixing before pull the bag, could be a poor sparge (if you sparged). There's a bunch of reasons why things can go wrong, but without more information, we really can't isolate the variables.

I'll check more into conversion and lauter efficiency, thanks

We stirred for about 5 min at dough in so I doubt it was that, we also stirred as we added grain slowly. Not sure on crush (besides asking for double crush), but I am thinking that may a big part of our problem. We didn't test PH as we didn't think is was that crucial for a porter. We stirred every 20 minutes and real well before we pulled the bag. We didn't sparge. What is the best sparge method without having another vessel to clean? Just hold out 2-3 gallons of water from the total volume needed and pour (@170 degrees) it over the bag as it hangs?

That's a pretty big beer for no-sparge, I'm with the group that says your 65% brew house is pretty good. Are you saying that you added 10% grain over the totals you have listed there, or is that your actual total grain bill?

My total in the first already had the 10% included.

Based on my calcuations, you were at 80-90% conversion efficiency, depending on what your final mash gravity was. There might be a few points in there that you could have gotten out with a finer crush, but not a ton.

Can you share the calculations? I am interested in how they are done.

The real losses are happening in the 2.25 gallons of strike water that are still hanging up there in your grain bag. Adding sparge water to rinse some of those sugars out will help your overall efficiency. Since you are already having to reserve a portion of the strike water to fit in the kettle, it might not be that hard to plan for 2-3 gallons of sparge next time.

Sounds like a sparge is in order, what is your sparge method?

I ran the grain bill and pre-boil numbers thru my mash simulator and came up with the following:

Apparent grain absorption rate = 0.072 gal/lb
Conversion Efficiency = ~ 85%
Lauter Efficiency = 70 - 71%
Mash Efficiency = ~ 60% (= Conversion Efficiency * Lauter Efficiency)​

The only ways to increase lauter efficiency are to reduce the grain absorption rate by squeezing more aggressively, or to add a sparge step.

The low hanging fruit is your conversion efficiency. Homebrewers can routinely achieve conversion efficiencies in excess of 95%. The biggest two factors in conversion efficiency are crush coarseness and mash time. The gelatinization step of conversion starts at the surface of the grits and proceeds towards the centers. The larger the grits (the coarser the crush) the longer the gelatinization takes to complete. Saccharification (starch to sugar conversion) cannot occur until the starch is gelatinized. So conversion cannot complete until gelatinization is complete. Thus coarser crushes need longer mash times.

Longer mash times will help, but may not be able to compensate totally for too coarse a crush. The amylase enzymes denature slowly at mash temps, and in a long enough mash with a coarse crush, you have a race going on between completing gelatinization and enzyme denaturing. And sometimes the enzymes lose, so that the conversion will never complete, no matter how long the mash.

Had you achieved 95% conversion in your mash, your efficiency numbers would have looked like this:

Conversion Efficiency = 95%
Lauter Efficiency = 69 - 70%
Mash Efficiency = ~ 66%
Pre-boil SG = 1.078​

And at 100% conversion efficiency, the numbers look like this:

Conversion Efficiency = 100%
Lauter Efficiency = ~ 69%
Mash Efficiency = ~ 69%
Pre-boil SG = 1.081 - 1.082
​

Can you share these calculations? I love calculations. What mash simulator are you using?
We mashed for 75 minutes, I really think that our crush is suspect.
I'll hit the LHBS up for what gap they crush at.
I used .08 for my grain absorption rate in my calculation for water volume. It was just a educated guess based on what I read others were using.​

 

[McKnuckle]

The wort/water that we pulled out of the bottom, was very dark and not plain water, but it was part of the total volume I had calculated, so it shouldn't dilute the overall volume going into the pre-boil....?

How early did you pull it after mashing in? It was dark because of the dark grains; the color comes out very quickly. But if the liquid was very low gravity, then it did dilute the gravity of the boil volume.

Think of it this way:

You could boil 9.75 gallons of 1.080 wort.

Or, you could boil 8.75 gallons of 1.080 wort and 1 gallon of 1.000 wort, which combine to be 9.75 gallons of 1.072 wort.

Did you measure pre-boil gravity BEFORE or AFTER you blended back the volume that had been pulled out - and how much volume was it?

(Also, if you had sparged with that extra water vs. just blended, it would have at least contributed to the lauter efficiency.)

 

[PsychoBiter]

How early did you pull it after mashing in? It was dark because of the dark grains; the color comes out very quickly. But if the liquid was very low gravity, then it did dilute the gravity of the boil volume.

Think of it this way:

You could boil 8 gallons of 1.050 wort.

Or, you could boil 7 gallons of 1.050 wort and 1 gallon of 1.000 wort, which combine to be 8 gallons of 1.044 wort (12% dilution).

Did you measure pre-boil gravity BEFORE or AFTER you blended back the volume that had been pulled out?

We pulled it off the bottom during mash in because all the grain wouldn't fit with the full volume of water into the keggle. We added it back in after we pulled the bag. It was stirred and the "pre-boil" SG was taken from there. It was maybe 1/3 of a gallon.

 

[McKnuckle]

Okay, so not an ideal use of the water, but 0.33 gal is not going to make or break things. I guess it's the crush!

 

[BeardedBrews]

Thank everyone so much for your input! Here is some more info....

You win the prize for epic multi-quote of the day!

I use Brewer's Friend http://www.brewersfriend.com/ which uses Gravity / Strike Volume to get conversion efficiency. I didn't save the recipe so I don't have handy the PPG that it assigned to each of the grains, but each grain is different. In truth, substituting an american 2-row for a german 2-row might have a noticeable impact on potential gravity.

<edit> Brewer's Friend has American 2-Row as 37ppg and German Pale as 39ppg. Depending on the grain bill, that could certainly be a few points in OG.

I haven't been doing a sparge since I went to the 15 gallon kettle. When I was on a 7 gallon I would heat probably 6 gallons to strike temperature, then pull a gallon or two out before I doughed in. After the mash I'd lift the bag and dunk the grains into that extra gallon or two of hot water just to "rinse" a little extra sugar out. Then squeeze and dump it in the wort.


I do suggest that you brew a couple more batches of varying strengths and colors before you start making changes. I always worry that the change I see in a single batch could have been random chance / grain / etc, and not the result of the change in my process. I try to do two or three batches to see what's actually happening.

-B

 

[PsychoBiter]

You win the prize for epic multi-quote of the day!

I use Brewer's Friend http://www.brewersfriend.com/ which uses Gravity / Strike Volume to get conversion efficiency. I didn't save the recipe so I don't have handy the PPG that it assigned to each of the grains, but each grain is different. In truth, substituting an american 2-row for a german 2-row might have a noticeable impact on potential gravity.

<edit> Brewer's Friend has American 2-Row as 37ppg and German Pale as 39ppg. Depending on the grain bill, that could certainly be a few points in OG.

I haven't been doing a sparge since I went to the 15 gallon kettle. When I was on a 7 gallon I would heat probably 6 gallons to strike temperature, then pull a gallon or two out before I doughed in. After the mash I'd lift the bag and dunk the grains into that extra gallon or two of hot water just to "rinse" a little extra sugar out. Then squeeze and dump it in the wort.


I do suggest that you brew a couple more batches of varying strengths and colors before you start making changes. I always worry that the change I see in a single batch could have been random chance / grain / etc, and not the result of the change in my process. I try to do two or three batches to see what's actually happening.

-B

What are your numbers with your 15 gallon kettle? I'd be interested in your set up. I don't think this keggle is going to work for the bigger beers and 7.5 gallon batches we like to brew.

I guess I need to get more familiar with what my LHBS sells so I can get better numbers on the grain they sell. I understand different malt masters even have different ppg numbers.

 

[BeardedBrews]

I don't generally make anything above a 1.070 beer, and actually haven't done more than 1.060 since I moved from extract to BIAB. For that, I can easily fit the grain and strike to get a 6-7 gallon batch in the keg. I think if I could get a 75% efficiency I could theoretically hold 10 finished gallons of 1.065 in the keg, but in practice I don't think I'd do that.

With the increased grain cost in the higher gravity beer I'd rather know that I'm going to hit my numbers. For me, I'd rather brew 4 gallon batches twice. It reduces the variables, and gives me a chance for a sanity check on the numbers in the second batch.

I am generally 85-95% conversion efficiency, I may actually be a little higher than that because I haven't been specifying the grain sources in Brewer's Friend. My Brew-House efficiency is between 70 and 80%, usually landing around 75%.

I have been using a random assortment of grain sources between online orders at the big names, the smaller names, and the two LHBS near me. This year I'm going to try to understand if the differences in brewhouse are more due to the grain, or due to the recipe, so I've bought my own grain mill. Where possible I will be buying grain in bulk, and will try to get the specialties all at least from the same LHBS.

 

[LLBeanJ]

We don't have a PH meter, I have read that the strips are worthless, especially in a dark beer. Anyway to determine without buying a meter? What would you suggest adding to correct for PH based on our grain bill and using RO water. I do know the RO water typically runs 6.8 on the PH scale, I used my pool tester to estimate.

I don't have a meter either, but I do have a municipal water report and I use the water calculator from Brewersfriend.com, which seems to get me pretty close. The reason I say that is after I started adjusting my water, my beers went from good, but nothing great, to very good. Fortunately, we have very soft water with a very low mineral content in my area and it seems to stay fairly consistent throughout the year. I realize that without a meter I'm mostly operating on faith, but my confidence is bolstered by the quality of the end product. At this point, I have no need for a meter and will continue doing what I've been doing until something suggests I need to make a change.

Since you are using RO, you pretty much will already know your water's starting point, as RO has essentially no minerals. However, for all grain brewing, at least for the mash, your water needs some minerals present and your pH does need to be reasonably managed. This is why I posted my comment. Using a water calculator, you can input your grain bill and RO water amounts for mash and sparge (if you sparge) and it should get you in the ball park. For a more complex water calculator, you can also check out the Bru 'n Water spreadsheet that can be found in the Brewing Science section of the forum, but I've found the Brewersfriend calculator works pretty well for my needs.

 

[tennesseean_87]

Maybe I missed it, but you mentioned adding grain to get higher eff. More grain doesn't correct lower eff to higher, but compensateshe for lower eff to still get your target og.

Also, I recommend using software like Brewtarget to do your calculations and scale your recipes to whatever eff you typically get (accounting for lower eff on high gravity batches).

 

[PsychoBiter]

Maybe I missed it, but you mentioned adding grain to get higher eff. More grain doesn't correct lower eff to higher, but compensateshe for lower eff to still get your target og.

Also, I recommend using software like Brewtarget to do your calculations and scale your recipes to whatever eff you typically get (accounting for lower eff on high gravity batches).

That make more sense, we exceeded the OG for the recipe (1.079 vs 1.089), but when I saw the potential for what grain we used, I got greedy and expected/wanted the higher OG that a higher efficiency would give me. We had never done BIAB so didn't know what to expect for efficiency. I just had 75% in my head for a big beer and was a little disappointed and wanted to get some ideas for next brew. One thing about not knowing what you are doing is that you learn a lot by messing up. We have been luck to make all good bears, but there are some things we can for sure improve on.

 

[paperairplane]

7.5 gallons of 8% beer in a keggle, BIAB is pretty maxed out.

What you do is be happy with 65% and call it a day. Lower ABV or less volume and you'll pick up a few points.

RDWHAHB

 

[pricelessbrewing]

Or do a sparge..

 

[Stonga]

Or....just be happy with the 65% and then put all the spent grain (still in the bag) into a fermenter then pour over about 10 litres of 70C water. Pull the bag and then check the gravity. Take a hyrodmeter reading to see if you can get another beer out of it.

If the gravity is low then add some DME.

More cheap beer!

Have a read around partigyle and or small beer.

 

[jdauria]

I get 65% using BIAB too. I've done a few things to tweak my process and nothing seems to work. Now I just use 65% as my target and everything turns out great.

Ditto here, no matter what I always hit between 65-67% efficiency, no matter what I do to improve it.

 

[flashcdog]

I just want to second what LLBeanJ has been saying to you regarding minerals and PH.

PH was perhaps the last thing I really paid attention to but since I have increased my efficiency to 80% +. I am a full volume mash guy too.

I also use RO water and get mine from one of those Glacier filter systems you find at a grocer.

While there could certainly be other culprits to your efficiency woes... I would definitely recommend reading up on mash PH. In my opinion one of the most underrated aspects of brewing for most of us novices...especially BIAB brewers.

And I am going to get blasted by water purists but just tweaking a little gypsum and calcium chloride is really all that is needed a little more or a little less depending on style.

 

[PsychoBiter]

Thanks, Adjusting mash water is the next step in improving our beer.