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What might I have done wrong, low OG- batch sparge

Mashing
#1

Looking for clues as to why my OG on my number 8 was about 18 points low.
20 lbs Pilsen malt
2.75lbs crystal 120 (had to sub for Belgian cars)
2 lbs brown sugar
1 lb cane sugar

Mashed grains at 148 with 7.5 gallons. Drained 3 gallons them remembered I forgot I add two gallons for absorption. I then added it mixed and continued draining. Ended up getting another 3 gallons runoff. Put another 6 gallons at 170 degrees , stirred, let it so 3-4 minutes and drained

Boiled 60 minutes with sugar additions coming at 10 minutes.

Checked OG after cooling about halfway through draining the boil pot and got an OG of 1.066
I usually get 80+% efficiency.

Any ideas on what could have gone wrong

#2

Just some possibilities:

  1. Didn’t boil off enough. Too much final volume.
  2. Bad crush.

Not sure of your batch size. Guessing 10g.

#3

7.5g + 2g + 6g = 15.5g total water
3g + 3g + 6g = 12g collected

~2.275g absorbed.

At an absorption of .1g / lb you’re missing about .5g - 1g of wort.

What was the pre-boil gravity of the 12g collected?

Larger grain bills = lower efficiency.

To compensate, check crush, sparge more and boil longer.

#4

[quote=“stickboy”]Larger grain bills = lower efficiency.

To compensate, check crush, sparge more and boil longer.[/quote]

Bingo!

#5

[quote=“dmtaylo2”][quote=“stickboy”]Larger grain bills = lower efficiency.

To compensate, check crush, sparge more and boil longer.[/quote]

Bingo![/quote]

Indeed! I had the same issue with an Oktoberfest I did a couple of months ago. I ordered my grains (precrushed) from a company that shall remain nameless (NOT NB) and when I received them, they seemed pretty coarsely crushed. Since I had no way to recrush them, I brewed the batch anyway, and the OG was well below what it should have been.Since I had a lot of grain left over from this particular order, I decided it was a good time to invest in a grain mill. When I received the mill, I proceeded to remill the remaining grain and brew a batch with it. The result? Slightly higher OG than calculated. :mrgreen:

My point? Crush is pretty critical. The first batch had a lot of almost whole kernels in it. The grain I recrushed looked similar to what NB precrushed grains look like.

One other thing: buy a bottle of Iodine and check your conversion. The small cost of the Iodine is good peace of mind.

#6

My final volume was about 11-11.5 gallons. I have brewed may beers with similar grain bills and have still had good efficiency. I did add my absorption water after I had drained 3 gallons and then only let the second runnings soak about 3 minutes. Could this be a contributor?

Any suggestions on how to increase the Gravity now? I did add one pound of sugar and one pound of DME that was boiled for 10 minutes in 4 cups of water. That raised my gravity up to 1.072.

Would honey affect the flavor, or does the honey all ferment out?

#7

[quote=“Roddy”]My final volume was about 11-11.5 gallons. I have brewed may beers with similar grain bills and have still had good efficiency. I did add my absorption water after I had drained 3 gallons and then only let the second runnings soak about 3 minutes. Could this be a contributor?

Any suggestions on how to increase the Gravity now? I did add one pound of sugar and one pound of DME that was boiled for 10 minutes in 4 cups of water. That raised my gravity up to 1.072.

Would honey affect the flavor, or does the honey all ferment out?[/quote]

I can’t come up with a scenario where the water additions you did would cause it

Honey will ferment out and leave no flavor

Was the grain crushed differently this time? Have you brewed this recipe before?

#8

I can’t come up with a scenario where the water additions you did would cause it

Honey will ferment out and leave no flavor

Was the grain crushed differently this time? Have you brewed this recipe before?[/quote]

One other thought. Could old grain be the cuplrit? My pilsen was probably 8 month sold. It was being stored in the 50 pound sack.

I have not brewed this recipe in the all grain version. I have brewed many with a similar grain bill. I almost always take a gravity check after mashing to get a guestimate on gravity after the boil. I didn’t this time because I have usually been right where I need to be.

I probably have 20-30 all grain batches under my belt and I cannot think of what I may have done differently this time.

#9

I doubt it, that time frame should be ok. I have used old grain, 3 yrs old, for making starter wort. It certainly produced a little less gravity than fresh grain, but not the %age you’ve experienced here.

#10

Figured I could piggy back off of this subject.

First all grain in the books. Per beersmith, my pre-boil gravity should have been 1.054 for the Dry Dock Urca Vanilla Porter. Hit 1.052. Now my post boil gravity is below that, 1.050. Boiled off from 6.25 to 5.75 gallons. Mashed with 1.25 quart/pound at 154.

  • 4.25 lbs English Maris Otter
  • 4.25 lbs Rahr 2-row Pale
  • 0.875 lbs. English Medium Crystal
  • 0.75 lbs. Flaked Barley
  • 0.5 lbs. English Chocolate Malt
  • 0.5 lbs. Belgian Aromatic Malt
  • 0.5 lbs. Belgian Special B
  • 0.25 lbs. English Black Malt

Can someone please edify me on this as I am befuddled.

#11

First question I would have for you, jabonneau, is: have you adjusted your measurements for temperature? Any specific gravity measurements with a hydrometer greater than 70 F need to be adjusted for temperature. There are adjustment tables available like these (both the same):

http://www.brew365.com/technique_hydrom ... ection.php http://www.ebrew.com/primarynews/ct_hyd ... ection.htm
#12

Yes, let the samples cool over night in my house, currently 66F. post boil gravity was to be 1.061, and is showing 1.050.

#13

That is scientifically impossible. One of the readings is wrong, plain and simple.

#14

Hmmmmmmmmmmmmmmmmmmmmmmmmm :?

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