Low OG Biab

[DefinitelyJon]

This was my third time with BIAB, and I keep ending up with a pretty low efficiency. I brewed a citra pale ale today and was left with a OG of about 1.044, while recipe says it should be near 1.054. I mashed for about an hour and 15 minutes, drained the bag, and gravity was about 1.038. Then boiled for an hour and was left with 6 gallons in kettle. Someone help me out as to why I keep undershooting. Here is the recipe I followed

7.5 Lbs 2 row
1 lb 60 L Crystal Malt
1 lb Dark Munich
.5 lb Flaked Barley
1 oz Citra(60 Minutes)
2 oz Citra(5 Minutes)
1 oz Citra (Dry Hop)
Mash at 152 for an hour

 

[The_Bishop]

What was your target batch size? If you're supposed to hit 5 gallons post boil and you're at 6, your gravity readings will be off.

Could be a few issues; grain crush, water volumes off, mash temperature stability, mash PH due to water...

 

[DefinitelyJon]

The water was off, it was supposed to be 5 gallons. I had 7.5 gallons total in the kettle to start, which was what was calculated. The ph looked good when I checked. The mash stayed at around 153-154 for that time. Maybe I should have boiled for longer due to so much excess water?

 

[LLBeanJ]

With your recipe, if based on a 5g batch size, you would hit 1.054 @ 73% efficiency. Increase the batch size to 6g and with the same efficiency, the OG should come in around 1.045. So, problem #1 looks to be volume related, i.e., you put 6g into the fermenter when the recipe was sized for 5g. Next time, either use less water or increase the size of your grain bill to match the intended volume into the fermenter.

Edit: I see you posted before my reply landed. Yes, you could have boiled off that extra gallon and that would have given you your target OG.

73% is not bad, but you should be able to get to at least 80%. You didn't mention a mash-out rest, so I assume you didn't do one. When I used to mash with the full batch volume, I found that the mash-out rest was good for a few more efficiency points, so you may want to try it. In lieu of the mash-out, you could try doing a small pour-over-grains sparge with cold water, which would yield about 5 more points. A finer crush might get you a few more points as well. If you do these things and still can't get to 80%, then you would probably want to look at your water with respect to how it is influencing your mash pH.

 

[DefinitelyJon]

Thanks llbeanj, I definitely need to calculate the water out right next time. I was thinking of doin of a mashout for the next batch and seein how well things improve. I did leave some water to rinse on the other batch and it seemed to bump up my efficiency by a little.

 

[misterkidd]

Some people squeeze out the bag after the mash for extra efficiency.

 

[DefinitelyJon]

I've been doin that which has helped me out a bit misterkidd

 

[soccerdad]

Should still be a good beer if your yeast works well.

 

[DefinitelyJon]

Yeah I'm sure it will be. I'll just have to try a different method next time

 

[wilserbrewer]

At the very least. I would put a mark on your brew spoon that indicates finished batch size post boil. As you boil, monitor your volumes. If you have excess, extend the boil, yet time your finish hops for the end of your anticipated adjusted boil. Might sound tricky but it is rather simple. Boiling off a couple extra pints is not the end of the world either, just top up kettle with a couple of spring water bottles.
FWIW, I typically boil to a volume, rather than an exact time, but shoot for an hour boil. Volume is more important than a 55 vs 75 minute boil IMO, w/ late hop additions timed to flameout of course.

ps: realize that boiling volume is about 4% more due to expansion, so figure a tad excess.

 

[DefinitelyJon]

Thanks wilserbrewer, after not knowing what volume of water I was left with last time I grabbed a long stick to cut notches in to see exactly where I was at in terms of water volume. Definitely should help next time I brew

 

[JONNYROTTEN]

Some people squeeze out the bag after the mash for extra efficiency.

I used a small pot lid to squish the grain after raising the basket.Got way more wort out and hit numbers exactly

 

[ram5ey]

Another mystery solved!

 

[JordanKnudson]

7.5 gallons at the start of the boil might take quite a bit to get down to a 5 gallon batch size. How did you calculate it? I notice that software like BeerSmith will significantly overshoot my needed water volumes if I don't very carefully craft my equipment profile in the software. I have often ended up with missed OGs thanks to this.

 

[DefinitelyJon]

I used the simplebiabcalculator, which all the others i checked calculated about the same amount for water. I started the mash with 7.5 gallons of water and was still left with 6.75 after the mash. so ended with about 6 gallons after the boil. I realize now also that some of those calculator may not calculate it right when you squeeze the hell outta the bag. I squeezed probly half a gallon back into the kettle.

 

[pricelessbrewing]

I used the simplebiabcalculator, which all the others i checked calculated about the same amount for water. I started the mash with 7.5 gallons of water and was still left with 6.75 after the mash. so ended with about 6 gallons after the boil. I realize now also that some of those calculator may not calculate it right when you squeeze the hell outta the bag. I squeezed probly half a gallon back into the kettle.

Yeah, simple is simple. Not a lot of features included, some variables can't be changed (such as grain absorption). Check out my calculator at pricelessbrewing.github.io/BiabCalc it's the most flexible calculator I've seen, more accurate than any other as it accounts for thermal expansion and has volume heights for each step in the brewing process, and you can change any variable you want.

 

[patrad]

I have a similar problem in that I was shooting for a final 5 gal but ended with 6 as I didn't get the evap I was expecting. Everything is cool now and finishing hops were added so I'm hesitant to re-boil. What will be the affect on final brew? If it's just less ABV I'm not too concerned. But will it significantly affect body/flavor? I have an OG of 1.057 (was shooting for 1.065) and by my calcs I have 66% efficiency into kettle and 74% efficiency into fermentor.

So then the answer for me is to shrink my water? Or water and grain bill?

 

[The_Bishop]

Maybe a combination of reduce water and boil harder?

 

[JordanKnudson]

I have a similar problem in that I was shooting for a final 5 gal but ended with 6 as I didn't get the evap I was expecting. Everything is cool now and finishing hops were added so I'm hesitant to re-boil. What will be the affect on final brew? If it's just less ABV I'm not too concerned. But will it significantly affect body/flavor? I have an OG of 1.057 (was shooting for 1.065) and by my calcs I have 66% efficiency into kettle and 74% efficiency into fermentor.

So then the answer for me is to shrink my water? Or water and grain bill?

In that situation, with flameout hops added already, your only real option is to leave it as is. The main thing that it will affect is ABV. There will likely be some reduction in body, too, but since that also has to do with your mash temps and grain bill, it may or may not be a noticeable change. It will probably be fine, though.

For next time, reduce your water. Look at what your boil-off was this time versus what you predicted, and adjust accordingly. (Also, remember that if you're boiling outside, changes in humidity can affect evaporation, although I generally find that this happens most significantly between seasons, not between two batches brewed in similar weather).

Don't reduce your grain bill. If your issue this time was a lower-than-anticipated OG due to over-estimating your water requirements, then you will need that same amount of grain with less water to achieve the desired concentration of sugars next time.

 

[Paradingbull]

With your recipe, if based on a 5g batch size, you would hit 1.054 @ 73% efficiency. Increase the batch size to 6g and with the same efficiency, the OG should come in around 1.045. So, problem #1 looks to be volume related, i.e., you put 6g into the fermenter when the recipe was sized for 5g. Next time, either use less water or increase the size of your grain bill to match the intended volume into the fermenter.

Edit: I see you posted before my reply landed. Yes, you could have boiled off that extra gallon and that would have given you your target OG.

73% is not bad, but you should be able to get to at least 80%. You didn't mention a mash-out rest, so I assume you didn't do one. When I used to mash with the full batch volume, I found that the mash-out rest was good for a few more efficiency points, so you may want to try it. In lieu of the mash-out, you could try doing a small pour-over-grains sparge with cold water, which would yield about 5 more points. A finer crush might get you a few more points as well. If you do these things and still can't get to 80%, then you would probably want to look at your water with respect to how it is influencing your mash pH.

Can you tell me the benefit of using cold water for the sparge? I mistakenly thought one would use hot (170F or so) for any sparge rinse.

 

[wilserbrewer]

Can you tell me the benefit of using cold water for the sparge? I mistakenly thought one would use hot (170F or so) for any sparge rinse.

Typically sparge water is hot, the point being made above is that cold also works fine, and in a pinch will solve a problem.

 

[RM-MN]

Can you tell me the benefit of using cold water for the sparge? I mistakenly thought one would use hot (170F or so) for any sparge rinse.

Hot water is better but cold water comes right out of the faucet and doesn't require another burner to heat it while I do have to heat water somewhere to use hot water sparge. The difference is pretty small since with BIAB brewing you typically use nearly full volume of water and only a small amount of sparge to make up volume when your pot isn't quite big enough. The wet grains will heat up that small amount of cold water so it dissolves the sugars just fine.