Low OG - Efficiency Issues

Homebrew Talk - Beer, Wine, Mead, & Cider Brewing Discussion Forum

Help Support Homebrew Talk - Beer, Wine, Mead, & Cider Brewing Discussion Forum:

RedL

Active Member
Joined
Dec 2, 2013
Messages
29
Reaction score
13
I have completed my first two brew sessions, identical batches, and I came up low on my OG both times. I am trying to figure out if it's something in my process causing this low efficiency. Any input would be appreciated.

This is a 5 gallon all-grain kit I had the brew store split in half and crush for me so I could do two 2.5 gallon batches. I did this BIAB.

2.5 gallon batch size BIAB
5.5 lb. grain bill
Strike water 160
Mash at 155 for 60 minutes
Boil 90 minutes
Target OG 1.054

The first batch I calculated the water amount with John Palmer's book for a 5 gallon batch and divided it in half, giving me 3.85 gallons starting. I was unable to control the temp well and had a very violent boil. I came up short 1 gallon and topped it up in the fermenter. My gravity reading was 1.040. Another forum member suggested maybe the water and wort didn't mix well throwing off my reading.

The second batch I used an online calculator for the water amount and started with 4.55 gallons. I modified my burner so I could control the boil this time. I also squeezed the bag to get as much wort as possible. I came out 1/2 gallon over. My OG was 1.046.

My boil off was obviously higher the first time. After I correct for that I think the water amount I used on the first batch was closer to the mark. Brewsmith says 4 gallons. Is it the water amount that is throwing me off on my gravity or another problem? Maybe the grain needs to be crushed differently? What am I missing?

Thanks everyone!
 

RM-MN

Supporting Member
HBT Supporter
Joined
Nov 26, 2010
Messages
15,068
Reaction score
6,127
Location
Solway
I had the brew store split in half and crush for me
This is the first clue. Brew stores crush to keep people from dealing with a stuck mash. This is important to the store as people get more irate at a stuck mash than in the fact that they need a little more grain to make up for the poorer efficiency.

With your BIAB system, you can handle a much finer crush and with that you will get a much higher efficiency. The only way to get the finer crush is to get yourself a mill. A cheap Corona mill works very well for BIAB as it can be tightened up until you almost get flour and with that two things happen, you efficiency goes way up and the time to get complete conversion goes down.

 

TheMadKing

Western Yankee Southerner and Brew Science Nerd
HBT Supporter
Joined
Jun 17, 2015
Messages
3,926
Reaction score
2,091
Location
Gainesville
This is the first clue. Brew stores crush to keep people from dealing with a stuck mash. This is important to the store as people get more irate at a stuck mash than in the fact that they need a little more grain to make up for the poorer efficiency.

With your BIAB system, you can handle a much finer crush and with that you will get a much higher efficiency. The only way to get the finer crush is to get yourself a mill. A cheap Corona mill works very well for BIAB as it can be tightened up until you almost get flour and with that two things happen, you efficiency goes way up and the time to get complete conversion goes down.


Agreed, crush is probably your main issue. It's also good practice to stir your mash several times throughout the hour to get good even hydration.

Your water volumes are also probability contributing to your issue, so that's just a matter if dialing it in with your process.

I'm not sitting in front of BeerSmith to check, but what NH efficiency were you expecting? Mid to low 70% range is what I found most common when I used BIAB. So it's important to have the right expectations.

Edit : I'll also add that you can compensate for your crush issues to a small extent by mashing longer. Go to 90 mins
 
Last edited:

bracconiere

Jolly Alcoholic
HBT Supporter
Joined
Jan 19, 2018
Messages
22,802
Reaction score
13,302
Location
S.AZ
hate to sound stupid, but how hot was the wort when you took it's gravity?

just asking because 1.040 at 130f, which is what my wort is at after sparging would be 1.053 corrected for temp, and your target OG almost spot on....
 
OP
OP
R

RedL

Active Member
Joined
Dec 2, 2013
Messages
29
Reaction score
13
This is the first clue. Brew stores crush to keep people from dealing with a stuck mash. This is important to the store as people get more irate at a stuck mash than in the fact that they need a little more grain to make up for the poorer efficiency.

With your BIAB system, you can handle a much finer crush and with that you will get a much higher efficiency. The only way to get the finer crush is to get yourself a mill. A cheap Corona mill works very well for BIAB as it can be tightened up until you almost get flour and with that two things happen, you efficiency goes way up and the time to get complete conversion goes down.

Thank you, that’s very helpful! I will try it on my next batch.

Agreed, crush is probably your main issue. It's also good practice to stir your mash several times throughout the hour to get good even hydration.

Your water volumes are also probability contributing to your issue, so that's just a matter if dialing it in with your process.

I'm not sitting in front of BeerSmith to check, but what NH efficiency were you expecting? Mid to low 70% range is what I found most common when I used BIAB. So it's important to have the right expectations.

Edit : I'll also add that you can compensate for your crush issues to a small extent by mashing longer. Go to 90 mins
It’s set to the default 72%. That estimates 1.054 which matches the instructions for the kit. I just got Beersmith yesterday so I’m still figuring out how to use it, and I had no idea what a BIAB efficiency should be. I think it would be under 60% to wind up where I did though. Is that unreasonably low for BIAB?
 
OP
OP
R

RedL

Active Member
Joined
Dec 2, 2013
Messages
29
Reaction score
13
hate to sound stupid, but how hot was the wort when you took it's gravity?

just asking because 1.040 at 130f, which is what my wort is at after sparging would be 1.053 corrected for temp, and your target OG almost spot on....
Good question, I let it cool to 70 degrees.
 
OP
OP
R

RedL

Active Member
Joined
Dec 2, 2013
Messages
29
Reaction score
13
then you can safely disregard my post.....another thought, what temp do you mash in at? or how do you get to mash temp?
I calculated it from a formula in John Palmers book. I heat to 160, then mash in and it stabilizes at. 155. I don’t have to touch it from there. It might lose 4 degrees in an hour.

That raises another question. Beersmith mentioned a 10 minute mash out at a higher temperature. I have never heard of that.
 

RM-MN

Supporting Member
HBT Supporter
Joined
Nov 26, 2010
Messages
15,068
Reaction score
6,127
Location
Solway
Thank you, that’s very helpful! I will try it on my next batch.


It’s set to the default 72%. That estimates 1.054 which matches the instructions for the kit. I just got Beersmith yesterday so I’m still figuring out how to use it, and I had no idea what a BIAB efficiency should be. I think it would be under 60% to wind up where I did though. Is that unreasonably low for BIAB?

My first try at BIAB I had to deal with only 80% brewhouse efficiency since I did a no sparge batch then. The Corona mill made that difference.

You can partially compensate for a coarse crush by leaving the grains in the mash for a longer period but there is a limit on how much that can improve the mash efficiency. Something about being able to extract the sugars from the large particles.

That raises another question. Beersmith mentioned a 10 minute mash out at a higher temperature. I have never heard of that.

That 10 minute mash out only applies to a conventional mash tun where one might use a fly sparge and would want (not sure why) to stop starch to sugar conversion during the long fly sparge. Ignore it in all other cases.
 

TheMadKing

Western Yankee Southerner and Brew Science Nerd
HBT Supporter
Joined
Jun 17, 2015
Messages
3,926
Reaction score
2,091
Location
Gainesville
Something about being able to extract the sugars from the large particles.

Sugar migrates from the inside of grain particles to the outside via osmosis. More time in a BIAB mash with a coarse crush allows for the sugar in solution to reach equilibrium with the sugar in the particles. That's why it only helps so much.

Grinding to flour somewhat bypasses this process by making the particles so small that the starch is effectively just in solution from the beginning.

That 10 minute mash out only applies to a conventional mash tun where one might use a fly sparge and would want (not sure why) to stop starch to sugar conversion during the long fly sparge. Ignore it in all other cases.

A mashout can also benefit head retention from glycoprotein synthesis and ending limit dextrinase activity that may be leftover from the mash additional alpha amylase activity even in BIAB.

Edit: Corrected my stupid per Vikeman's good call below
 
Last edited:

Birrus

Member
Joined
Mar 28, 2017
Messages
24
Reaction score
15
BIAB is the only method I've used since switching to AG 4 years ago. I agree with everything that's been said. Finer crush translates into higher efficiency. If buying a mill is not in your plans (I don't own one), simply ask the LHBS to crush the grains differently for you. Mashing for longer, say an extra 30 minutes, might give you those extra gravity points you chase (I know the experts claim the difference is minimal, but according to my experience, there's a difference). I have also noticed that "rinsing" ("sparging") my grains with 170F water after mashing gives me some extra gravity points as well.
Having said all that, I no longer do any of those things (except the crush part; my LHBS already know how to mill my grains). After many batches, I have determined what my efficiency is when following the same process. I simply adjust the recipe to get what I want (buying that extra pound of grain, for instance), and I hit the calculated numbers more often than not.
IMO, you should apply changes to your process that incorporate some of the good advice given in this forum; once that process is repeatable, calculate your efficiency and use that number when creating your recipes, adjusting the ingredients accordingly.
This is all assuming your instruments are calibrated, of course. :bigmug:
 

VikeMan

It ain't all burritos and strippers, my friend.
Joined
Aug 24, 2010
Messages
4,552
Reaction score
3,920
IMO, you should apply changes to your process that incorporate some of the good advice given in this forum; once that process is repeatable, calculate your efficiency and use that number when creating your recipes, adjusting the ingredients accordingly.

I would add: "use that number," adjusted for grain bill size.
 

Birrus

Member
Joined
Mar 28, 2017
Messages
24
Reaction score
15
I would add: "use that number," adjusted for grain bill size.
It is my understanding the efficiency is not dependent on grain bill size, but equipment and process instead. Efficiency remains the same for a system regardless of the grain bill. It would only need to be adjusted for changes in process and/or equipment profile.
 

VikeMan

It ain't all burritos and strippers, my friend.
Joined
Aug 24, 2010
Messages
4,552
Reaction score
3,920
It is my understanding the efficiency is not dependent on grain bill size, but equipment and process instead. Efficiency remains the same for a system regardless of the grain bill. It would only need to be adjusted for changes in process and/or equipment profile.

Sorry, but your understanding is incorrect. This can be modeled mathematically, but here's the gist, from a presentation I did a couple years ago...

"Recipes with larger grain bills (but the same pre-boil volume) require more total water, because of more grain wort absorption. So the ratio of absorbed wort to total wort (including absorbed) is larger. Therefore a smaller percentage of the total sugars/dextrins produced makes it to the kettle."

Full Presentation:
 

TheMadKing

Western Yankee Southerner and Brew Science Nerd
HBT Supporter
Joined
Jun 17, 2015
Messages
3,926
Reaction score
2,091
Location
Gainesville
Sorry, but your understanding is incorrect. This can be modeled mathematically, but here's the gist, from a presentation I did a couple years ago...

"Recipes with larger grain bills (but the same pre-boil volume) require more total water, because of more grain wort absorption. So the ratio of absorbed wort to total wort (including absorbed) is larger. Therefore a smaller percentage of the total sugars/dextrins produced makes it to the kettle."

Full Presentation:
1082EDCF-2A45-455C-8494-C95BBA9A2F58.jpeg


Here is a plot of the effect that a friend of mine made for his system so he could predict his efficiency for a given target OG and a given boil length (i.e. Sparge amount). It works for my system as well.

Sorry about the glare
 

Birrus

Member
Joined
Mar 28, 2017
Messages
24
Reaction score
15
Sorry, but your understanding is incorrect. This can be modeled mathematically, but here's the gist, from a presentation I did a couple years ago...

"Recipes with larger grain bills (but the same pre-boil volume) require more total water, because of more grain wort absorption. So the ratio of absorbed wort to total wort (including absorbed) is larger. Therefore a smaller percentage of the total sugars/dextrins produced makes it to the kettle."

Full Presentation:
I stand corrected. Interesting reading. Thank you. 😉 I assume one of the solutions in cases like this would be having a larger pre-boil volume then, and boiling for longer. Any ballpark idea of the percentage difference when brewing only 5 gallons? I ask because I have not noticed it, but then again, I always end up with a larger pre-boil volume when brewing big beers, I guess instinctively, lol. Thank you!!!
 

TheMadKing

Western Yankee Southerner and Brew Science Nerd
HBT Supporter
Joined
Jun 17, 2015
Messages
3,926
Reaction score
2,091
Location
Gainesville
I stand corrected. Interesting reading. Thank you. 😉 I assume one of the solutions in cases like this would be having a larger pre-boil volume then, and boiling for longer. Any ballpark idea of the percentage difference when brewing only 5 gallons? I ask because I have not noticed it, but then again, I always end up with a larger pre-boil volume when brewing big beers, I guess instinctively, lol. Thank you!!!

See my chart above for a ballpark. That is system dependant data so it won't be exactly right for you.

Your preboil volume should be calculated based on your desired volume into the keg - losses in the fermenter to trub and samples - (boil off rate in gallons/hr * # hrs boiled).

So your preboil amount should always be the same for a given boil time. A longer boil means more preboil volume, which means more sparging, which means more total sugars end up in the kettle, which means more lauter efficiency
 

VikeMan

It ain't all burritos and strippers, my friend.
Joined
Aug 24, 2010
Messages
4,552
Reaction score
3,920
Any ballpark idea of the percentage difference when brewing only 5 gallons? I ask because I have not noticed it, but then again, I always end up with a larger pre-boil volume when brewing big beers, I guess instinctively, lol. Thank you!!!

It depends on your system and process. But if you know the efficiency you get with your system for a given grain weight, you can load your system paremeters and base recipe into BrewCipher, then use the Mash Efficiency Predictor to estimate the change in efficiency for a different grain weight. You can also estimate the change from going no-sparge to (single batch) sparge or vice versa, either separately or in conjunction with grain bill size change.

With BIAB it's a little simpler (no deadspaces/transfer losses/etc. to consider), and if you don't need a new "all-in-one" brewing solution, @doug293cz's sheet might be a good solution for you.
 

doug293cz

BIABer, Beer Math Nerd, ePanel Designer, Pilot
Staff member
Mod
HBT Supporter
Joined
May 14, 2014
Messages
13,250
Reaction score
10,038
Location
Renton
I stand corrected. Interesting reading. Thank you. 😉 I assume one of the solutions in cases like this would be having a larger pre-boil volume then, and boiling for longer. Any ballpark idea of the percentage difference when brewing only 5 gallons? I ask because I have not noticed it, but then again, I always end up with a larger pre-boil volume when brewing big beers, I guess instinctively, lol. Thank you!!!
Here's a system independent chart that shows lauter efficiency vs. the ratio of grain bill weight to pre-boil volume for 0, 1, 2, & 3 sparge steps for two different grain absorption rates (0.12 gal/lb is typical for a traditional MLT, and 0.06 would be for a fairly well squeezed BIAB.) Fly sparge cannot be modeled in the general case, but a well conducted fly sparge should have a lauter efficiency 2 - 3 percentage points higher than the highest solid line in the chart.

I use the ratio of grain bill weight to pre-boil volume as that makes the data independent of batch size. 12 lb of grain with 6.5 gal pre-boil is the same as 24 lb with 13 gal pre-boil. This means if you want to make a RIS with 24 lb of grain vs. your normal 12 lb, and your batch size is the same, you have to double your pre-boil volume to keep the lauter efficiency the same. That would be a lot of extra water to boil off.

Mash efficiency is conversion efficiency times lauter efficiency. If your conversion efficiency is consistent, then you can use the chart to predict mash efficiency for different grain bill sizes. Brewhouse efficiency is just mash efficiency reduced by your post-boil volume losses. The brewhouse efficiency adjustment is always system dependent.

Efficiency vs Grain to Pre-Boil Ratio for Various Sparge Counts.png


Brew on :mug:
 

doug293cz

BIABer, Beer Math Nerd, ePanel Designer, Pilot
Staff member
Mod
HBT Supporter
Joined
May 14, 2014
Messages
13,250
Reaction score
10,038
Location
Renton
It depends on your system and process. But if you know the efficiency you get with your system for a given grain weight, you can load your system paremeters and base recipe into BrewCipher, then use the Mash Efficiency Predictor to estimate the change in efficiency for a different grain weight. You can also estimate the change from going no-sparge to (single batch) sparge or vice versa, either separately or in conjunction with grain bill size change.

With BIAB it's a little simpler (no deadspaces/transfer losses/etc. to consider), and if you don't need a new "all-in-one" brewing solution, @doug293cz's sheet might be a good solution for you.
Here's my spreadsheet. Best to download a copy for Excel or LibreOffice to make best use of it. The sheet allows you to adjust all of the factors that affect mash efficiency for 0 - 3 sparge steps. A modified version of this sheet was used to create the chart in my previous post.

Brew on :mug:
 

wepeeler

Supporting Member
HBT Supporter
Joined
May 31, 2018
Messages
1,294
Reaction score
2,451
Location
CT
Thank you, that’s very helpful! I will try it on my next batch.


It’s set to the default 72%. That estimates 1.054 which matches the instructions for the kit. I just got Beersmith yesterday so I’m still figuring out how to use it, and I had no idea what a BIAB efficiency should be. I think it would be under 60% to wind up where I did though. Is that unreasonably low for BIAB?
Another thing to add to all the good information in this thread is to make sure your equipment profile is set up as accurately as possible in Beersmith. I struggled hitting numbers when I first started using BS, and it was mainly because my volumes were off. It's also harder to predict when adding additional water after the boil if you don't have initial volumes (starting volume, grain absorption, boil off etc) measured accurately and correctly. The software is only as smart as the information that is dialed in. After a few batches, you should be able to get a handle on your system and get more accurate final numbers.
 
Top