Dubious Hydrometer Reading - Lowww Efficiency??

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BarleyThief37

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First stab at partial mash/Brew-in-bag last Saturday. Recipe as follows:

(fermentables)
6.75lb 2-row
1.25lb Caramel 40L
3.3lb LME - Amber
8oz dextrose
8oz maltodextrin

I used a throw-away mesh grain bag from LHBS for the 8lbs of grain - nearly maxed the capacity of that bag. Did the mash for 1hr at 154degF in my 5gal kettle on the stovetop. Note to self - 8lbs is the MAX I can mash in 5gal kettle.

OG was predicted at around 1.077, however the measurement I got was 1.051 - according to my calcs, this is around 35% efficiency in the mash. Is this even possible - seems extraordinarily LOW. Also, every 10-15mins during the mash I was jabbing and prodding the hell out of the grain bag to help the mash.

I did have to add ~5qts of water to meet the 5gal batch after boil, and honestly didn't mix too well because I'm going no-chill, and will stir/aerate in the morning when I pitch the yeast.

Could the poor hydrometer reading be attributed to water/wort segregation or something of that nature, or did I just completely botch my first partial mash?...In terms of efficiency that is...no homebrewer I know has ever found 1051 OG to be undrinkable:)

Thanks

BarleyThief
 
Could the poor hydrometer reading be attributed to water/wort segregation or something of that nature, or did I just completely botch my first partial mash?...In terms of efficiency that is...no homebrewer I know has ever found 1051 OG to be undrinkable:)

Could be the cause. Did you crush the grains or did the shop? That could also be a factor.
 
Did you measure your reading at the correct temperature? That could also account for any off OG readings.
 
Last edited:
First stab at partial mash/Brew-in-bag last Saturday. Recipe as follows:

(fermentables)
6.75lb 2-row
1.25lb Caramel 40L
3.3lb LME - Amber
8oz dextrose
8oz maltodextrin

I used a throw-away mesh grain bag from LHBS for the 8lbs of grain - nearly maxed the capacity of that bag. Did the mash for 1hr at 154degF in my 5gal kettle on the stovetop. Note to self - 8lbs is the MAX I can mash in 5gal kettle.

OG was predicted at around 1.077, however the measurement I got was 1.051 - according to my calcs, this is around 35% efficiency in the mash. Is this even possible - seems extraordinarily LOW. Also, every 10-15mins during the mash I was jabbing and prodding the hell out of the grain bag to help the mash.

I did have to add ~5qts of water to meet the 5gal batch after boil, and honestly didn't mix too well because I'm going no-chill, and will stir/aerate in the morning when I pitch the yeast.

Could the poor hydrometer reading be attributed to water/wort segregation or something of that nature, or did I just completely botch my first partial mash?...In terms of efficiency that is...no homebrewer I know has ever found 1051 OG to be undrinkable:)

Thanks

BarleyThief

When and how did you take the sample? If you took it after you added the water you just didn't get good mixing and thus got an erroneous reading. If you took the sample right from the mash tun without stirring you could also have a bad reading. For example, I used my refractometer to take 2 reading during the mash of my latest brew. The first one was just a couple minutes into the mash and the reading was 1.015, At 30 minutes i took another sample off the top of the mash before pulling the bag and that reading was 1.005. I know that in some religions people can unconvert but I don't think that that happens in brewing. After pulling the bag and stirring up the wort the gravity was 1.047, just were predicted for this beer.

You also might have a problem with the bag if it constricts the grains too much. I use a bag that fits the whole inside of the pot so the grains are mixed into the entire amount of water.

The third possibility is the milling of the grains. Many LHBS have their mills set to accommodate the people using a conventional mash tun and mill so nobody get a stuck sparge. While good for business as nobody complains about being milled too fine and people just buy more grain to make it work, it pretty much guarantees a low efficiency. If your grains were crushed even worse than average, that would contribute to the low efficiency and could be the entire cause.
 
Could be the cause. Did you crush the grains or did the shop? That could also be a factor.

My brew buddy came over with his mill. It's been calibrated, and the grain was pretty well crushed up; lots of flowery chalky material and busted up husks.

Did you measure your reading at the correct temperature? That could also account for any off OG readings.

The brew was no-chill, and OG was taken at ambient basement ~65degF (perfect for fermentation I might add)

And next time for sure I'll by the in-pot brew bags. The grain was definitely not free-floating, as 8lbs in the mesh bags was pretty tight. I might also consider stepping down to a 4lb mash if I do go disposable; glorified 'steeping' grains.

For the record I may call it OG 1.077, and just assume an off-reading:mug:
 
My brew buddy came over with his mill. It's been calibrated, and the grain was pretty well crushed up; lots of flowery chalky material and busted up husks.



The brew was no-chill, and OG was taken at ambient basement ~65degF (perfect for fermentation I might add)

And next time for sure I'll by the in-pot brew bags. The grain was definitely not free-floating, as 8lbs in the mesh bags was pretty tight. I might also consider stepping down to a 4lb mash if I do go disposable; glorified 'steeping' grains.

For the record I may call it OG 1.077, and just assume an off-reading:mug:

Get yourself a Wilserbrewer bag custom sized to fit your pot.

65 ambient could be a tad warm, your wort is pushing 70+ during fermentation.
 
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