Missing OG but not Pre-Boil Gravity

[THVbrew]

On my last few brews, I have been hitting or exceeding my Pre-Boil Gravity, but have been coming up a few points short on the OG in my fermentor. I do 2.5 gallon BIAB batches and have an avg. mash efficiency of 80%, but my brewhouse efficiency is low at an avg. of 62%. Below is a little chart on my last three brews.

__________Pre-Boil Est.___Pre-Boil Act.___Pre-Boil Vol. Est.___Pre-Boil Vol. Act___OG Est.___OG Act.
Brew 1_______1.049________1.050__________3.57 gal___________3.80 gal_______1.059_____1.056
Brew 2_______1.049________1.049__________4.02 gal___________4.10 gal_______1.066_____1.061
Brew 3_______1.052________1.054__________3.72 gal___________3.80 gal_______1.065_____1.057



Any ideas on why I am not hitting the OG in my fermentor even though i am hitting my pre-boil gravity? I build my recipes in BeerSmith based on a Total Efficiency of 65%.

 

[Oginme]

Without volume measurements at each step, it is difficult to determine exactly where you are off in your BeerSmith profiles. Basically, it could suggest that your estimated boil off rate is too high versus your actual values. However, without the associated volumes pre-boil, post-boil and losses it would be only the most likely explanation.

 

[Zzyzx3]

If you are hitting your pre boil gravity, but short on original gravity, something is off with the boil off rate and the final volume of beer. It might be estimating too high of a boil off rate and you might be ending up with a higher volume of liquid at the end of the boil.

 

[tjmac5071]

Boil more vigorously or adjust your gal/hr boil off in beersmith settings. I think default is 1gal hr. You can either do an actual test and adjust settings after that, or adjust down to .8 or something and see where you land, then fine tune.

 

[RM-MN]

On my last few brews, I have been hitting or exceeding my Pre-Boil Gravity, but have been coming up a few points short on the OG in my fermentor. I do 2.5 gallon BIAB batches and have an avg. mash efficiency of 80%, but my brewhouse efficiency is low at an avg. of 62%. Below is a little chart on my last three brews.

__________Pre-Boil Est.___Pre-Boil Act.___OG Est.___OG Act.
Brew 1_______1.049________1.050________1.059____1.056
Brew 2_______1.049________1.049________1.066____1.061
Brew 3_______1.052________1.054________1.065____1.057



Any ideas on why I am not hitting the OG in my fermentor even though i am hitting my pre-boil gravity? I build my recipes in BeerSmith based on a Total Efficiency of 65%.

If you are only getting 80% mash efficiency with BIAB, you need to think about why that is. Many of the BIAB brewers are expecting mash efficiency in the mid 90's. Then you need to consider why your brewhouse efficiency is at 62% when many of the BIAB brewers exceed 80% and some are touching the 90% efficiency. From there, once you have the wort into the pot at the correct pre-boil, your post boil gravity only depends on the amount of water your boil off to concentrate the sugars collected.

 

[THVbrew]

On my last few brews, I have been hitting or exceeding my Pre-Boil Gravity, but have been coming up a few points short on the OG in my fermentor. I do 2.5 gallon BIAB batches and have an avg. mash efficiency of 80%, but my brewhouse efficiency is low at an avg. of 62%. Below is a little chart on my last three brews.

__________Pre-Boil Est.___Pre-Boil Act.___Pre-Boil Vol. Est.___Pre-Boil Vol. Act___OG Est.___OG Act.
Brew 1_______1.049________1.050__________3.57 gal___________3.80 gal_______1.059_____1.056
Brew 2_______1.049________1.049__________4.02 gal___________4.10 gal_______1.066_____1.061
Brew 3_______1.052________1.054__________3.72 gal___________3.80 gal_______1.065_____1.057



Any ideas on why I am not hitting the OG in my fermentor even though i am hitting my pre-boil gravity? I build my recipes in BeerSmith based on a Total Efficiency of 65%.

I have added my pre-boil volume est and actual to the table in my original post. I haven't been keeping a good record of the amount of wort left behind in the kettle after transferring 2.5 gallons to the fermentor. It seems like I need to lower the boil off figure in BeerSmith. I brew on a pretty weak electric range that can hardly get 4 gallons to a decent boil.

My boil off rate for a 60 min boil is .50 gal and the loss to Trub and Chiller is set at .65 gal. Thinking i should lower the loss to trub figure now that I am convinced trub in the fermentor will not negatively impact my beers. I had this set higher so I could transfer as much clear wort as possible.

 

[RM-MN]

I have added my pre-boil volume est and actual to the table in my original post. I haven't been keeping a good record of the amount of wort left behind in the kettle after transferring 2.5 gallons to the fermentor. It seems like I need to lower the boil off figure in BeerSmith. I brew on a pretty weak electric range that can hardly get 4 gallons to a decent boil.

My boil off rate for a 60 min boil is .50 gal and the loss to Trub and Chiller is set at .65 gal. Thinking i should lower the loss to trub figure now that I am convinced trub in the fermentor will not negatively impact my beers. I had this set higher so I could transfer as much clear wort as possible.

It seems that you may have fallen victim to the addage, "to get clear beer you need clear wort". You don't. Any wort you leave in the pot is potential beer that you throw away. I dump everything in, even the thick proteins and hop debris. It all settles out and give me clear beer.

 

[THVbrew]

Indeed I did. I thought it would impact clarity and potentially result in off flavors.

What do you use as the loss due to Trub and chiller figure in BeerSmith?

 

[McKnuckle]

I use ZERO for post-boil losses after considering the shrinkage factor and hop absorption. Like RM-MN, I pour it all into the fermenter. The only efficiency score I care about is the mash part. Brewhouse doesn't do much for me so I don't track it.

 

[olotti]

Indeed I did. I thought it would impact clarity and potentially result in off flavors.

What do you use as the loss due to Trub and chiller figure in BeerSmith?

I've had the same probs as you when I first started beersmith. I had to adjust my preboil volume and boil off rates so now I know that if I do miss my og it's strictly because I didn't boil off enough. So I stop my boil at just under 6 gallons I lose about 1/2 a gallon to chiller loss and shrinkage and I take everything into my primary to get 5.5 gal and I always bottle 5 gal if not slightly more. A good cold crash will compact all the trub and hop debris.

 

[eelpout]

I can say that when was doing 5 and 10 gallon batches I had no problems with volumes and gravities using beersmith.
The second I started doing 3 gallon batches it is rare to have any of that come out right. And I'm using the same mashtun same kettle.

 

[THVbrew]

I can say that when was doing 5 and 10 gallon batches I had no problems with volumes and gravities using beersmith.
The second I started doing 3 gallon batches it is rare to have any of that come out right. And I'm using the same mashtun same kettle.

Has anyone else noticed this doing smaller than 5 gallon batches?

 

[McKnuckle]

Not really. I brew almost all 2-3 gallon batches and have things dialed in pretty well. It helps that I use an electric setup in an indoor space where the air is stable. There are no humidity fluctuations, wind, or variances in my boil intensity due to equipment settings.

I use slightly different boil-off rates depending on my boil volume, since it increases slightly as the volume decreases (same equipment setting makes for a bit more vigor at lower volumes). For example, 1.08 gal/hr at 4 gallons, 1.12 gal/hr at 3 gallons.

I also weigh my water and grains to the gram, so there's more accuracy/precision. I weigh hops to 0.1 grams. At smaller quantities, any error has more impact on the estimates.

 

[Oginme]

I can say that when was doing 5 and 10 gallon batches I had no problems with volumes and gravities using beersmith.
The second I started doing 3 gallon batches it is rare to have any of that come out right. And I'm using the same mashtun same kettle.

I have a different equipment profile for my 10 liter batches (~2.8 gal) versus my 16 liter and my 20 liter set-ups. Even with the 16 liter and 20 liter, I get a different mash efficiency (using the same mash tun). Just enough to make a ~4 point difference in OG.

 

[madscientist451]

When I started brewing, I was carefully measuring amount of strike water, stirring and taking the temp of the mash, being fussy how much sparge water and doing many other things that basically extended the brew day by an hour or more. After a while, I realized brewing is supposed to be a fun hobby and not so much work. I read and listened to a bunch of podcasts about how to simplify things and now have a much more relaxed and enjoyable brew day.
So having said that, do you really need to worry about hitting your numbers?
From here it seems like your brewing software doesn't have the correct evaporation rate for your brew pot/heat source. That should be easy enough to test, but not sure if you can enter that in Brewsmith.
Another way to hit your numbers is just add a little more grain.
Your 3 brews are off by an average of .005, so just add a little more base malt to hit those points.
But the real question is: Are you happy with the way the beer is coming out? Hitting all your estimated gravity points doesn't guarantee a good beer. The beer may actually be better with a lower OG, the only way to prove that its not, is to do a side by side analysis.
I make a lot of clones of highly rated beers and seldom hit the exact gravity estimations provided in a recipe, but in side by side blind taste test the home brew version is almost always the preferred beer.
So relax, you can be fussy with the process or not, the important thing is to enjoy your brewing time and your beer.

 

[eelpout]

Years ago, I used to be exactly what you are saying right now...
But I grew out of the... Well this beer is great and I don't care how it got that way. Or the... Welp,, something is off here, so I'll just do (x) to make up for it because I don't care why it happened if I can work around it.

Yes I can change the boil off, yes I can and have added or removed grains to hit what I want. and no I'm not worried about hitting other people's numbers. I wanna be able to hit relatively close to what I enter into Beersmith,, the first time and not have to fudge the numbers on the fly on brew day even though I am perfectly capable of doing so. It should be right right out of the gate.

I'm not that awful worried about hitting numbers dead nuts on but I am curious as to why Beersmith has always seemed to not like small batches for me. While standard size batches are perfectly fine.

And I don't think it's boil off as I have measured that several times over the years. I have though been leaning twards the strike and mash water volumes being calculated wrong somehow for the less than 5 gallon batches.
And I also think it may be with the water absorption calc.

Example. And just off the top of my head as I have no notes Infront of me. If I make beer A with say... 5 lbs of 2 row I will get X for my first running volume. But if I use the same recipe but switch in wheat it, BS still tells me I should be getting X for my volume but in reality I get X-.25

If I hadn't made these two recipes as often as I had, I might be thinking it's my boil off that's going funny.

Like I said,, I have been adjusting those as needed as brew progresses, and then adjusting in the software.
This may sound like dialing in, but it isn't linear across all recipes or brews. And it's don't do this in bigger volumes.

 

[Aristotelian]

When I started brewing, I was carefully measuring amount of strike water, stirring and taking the temp of the mash, being fussy how much sparge water and doing many other things that basically extended the brew day by an hour or more. After a while, I realized brewing is supposed to be a fun hobby and not so much work. I read and listened to a bunch of podcasts about how to simplify things and now have a much more relaxed and enjoyable brew day.
So having said that, do you really need to worry about hitting your numbers?
From here it seems like your brewing software doesn't have the correct evaporation rate for your brew pot/heat source. That should be easy enough to test, but not sure if you can enter that in Brewsmith.
Another way to hit your numbers is just add a little more grain.
Your 3 brews are off by an average of .005, so just add a little more base malt to hit those points.
But the real question is: Are you happy with the way the beer is coming out? Hitting all your estimated gravity points doesn't guarantee a good beer. The beer may actually be better with a lower OG, the only way to prove that its not, is to do a side by side analysis.
I make a lot of clones of highly rated beers and seldom hit the exact gravity estimations provided in a recipe, but in side by side blind taste test the home brew version is almost always the preferred beer.
So relax, you can be fussy with the process or not, the important thing is to enjoy your brewing time and your beer.

Exactly. Consistency is the key. If you are off by the same amount every time, just adjust your recipe, don't change your process. Getting the same results every time is a great problem to have.

I only get 65% using BIAB. I have no idea why, but I have no urge to change because I just adjust my recipe and hit my numbers consistently.

 

[madscientist451]

Years ago, I used to be exactly what you are saying right now...
But I grew out of the... Well this beer is great and I don't care how it got that way. Or the... Welp,, something is off here, so I'll just do (x) to make up for it because I don't care why it happened if I can work around it.

I wanna be able to hit relatively close to what I enter into Beersmith,, the first time and not have to fudge the numbers on the fly on brew day even though I am perfectly capable of doing so. It should be right right out of the gate.

I'm not that awful worried about hitting numbers dead nuts on but I am curious as to why Beersmith has always seemed to not like small batches for me. While standard size batches are perfectly fine.

You've had success using Beersmith with standard sized batches but not with smaller batches. You've accounted for boil off. So if you are using the same process, its logical to think that there something in the Beersmith software that doesn't account for the smaller batch size or other variables you may or may not be aware of.
Perhaps contact Brad Smith directly and see what he says?

 

[McKnuckle]

I don't use Beersmith any more, but if you are using a percentage figure for boil-off vs. a static volume figure, that could be an easy culprit. The percentage will be far higher for a smaller batch.