Big difference in measured OG vs calculator? Can my efficiency really be that bad?

[Oaky]

So I just brewed this last night: http://hopville.com/recipe/201126/imperial-ipa-recipes/oceanfarer

Here is situation. I took the gravity reading at 90 degree f - and it came out to 1.050. Kind of weird for a 7 pd of grain + 2 pd of candi sugar and 5 pds of LME etc. It was a solid 6G batch but I don't see how I can have a calculated 1.076 with a 65% efficiency and end up with 1.050. I mean - I'd have to be 30% efficient or something!
So what do you guys think? Bad hydrometer?
The brew seems to be doing great - smells awesome, it's bubbling within 6 hours of pitching - so all is well there, it's just the math that bugs me!

malt and fermentables
% LB OZ Malt or Fermentable ppg °L
33% 5 0 Light/Pale Malt Extract Syrup info 36 5
13% 2 0 American Two-row Pale info 37 1
13% 2 0 Belgian Candy Sugar Amber info 36 75
13% 2 0 American Two-row Pale info 37 1
13% 2 0 Honey Malt info 37 25
7% 1 0 Crystal 40L info 34 40
7% 1 0 Honey info 35 1

Batch size: 6.0 gallons Original Gravity
1.050 measured
(1.076 estimated)
Final Gravity
1.020
(1.018 to 1.022)
Color
20° SRM / 40° EBC
(Light Brown to Medium Brown)
Mash Efficiency
65%
hops
use time oz variety form aa
boil 60 mins 0.5 Simcoe info pellet 13.3
boil 60 mins 1.0 Sorachi Ace info pellet 12.2
boil 60 mins 0.5 Nugget info pellet 13.0
boil 15 mins 0.5 Nugget info pellet 13.0
boil 15 mins 0.5 Sterling info pellet 6.3
boil 15 mins 0.5 Cluster info pellet 7.0
boil 5 mins 0.5 Sterling info pellet 6.3
boil 5 mins 0.5 Cluster info pellet 7.0
boil 5 mins 0.5 Simcoe info pellet 13.3

Boil: 3.0 avg gallons for 60 minutes Bitterness
25.4 HBU
44.4 IBU
ƒ: Tinseth
BU:GU
0.59
yeast
Safbrew S-33 Dry Yeast info
ale yeast in dry form with medium to high flocculation
Alcohol
7.5% A.B.V.
5.8% A.B.W.
Calories
251 per 12 oz.

 

[RLinNH]

Did you do the math as the Wort was at 90 Degrees? If not, that's your problem.

 

[Ichthy]

Did you do a partial boil?

If so you probably didn't mix the top off water well enough with the wort and the gravity came out lower. You should correct for temp, but you won't see a 20 point difference in temp correct as previous poster suggested.

 

[ChshreCat]

Did you do a partial boil?

If so you probably didn't mix the top off water well enough with the wort and the gravity came out lower. You should correct for temp, but you won't see a 20 point difference in temp correct as previous poster suggested.

+1 if this was a partial boil I'd be 99.9 percent sure this is what happened. Happens all the time.

 

[david_42]

There has to be some problem with your OG measurement or mixing, because just the extract, candi and honey add up to 1.050. I've never had much faith in hot gravity measurements.

You have two entries for 2-row pale. Is that correct for 4 lbs total?

 

[Oaky]

Thanks for the posts -

Few answers: First - yes 2x2pd of 2 row for a total of 4pd. One came as part of a kit from Austin (ty Forrest!) the second I added to beef it up. I used one large 4G pot for all the grain and a separate smaller kettle (2.5g) for the hops and susequently LME. I then mixed them both together - I was very careful about hot wort areation - but the only top off water was a sparge on the grain which was done in a different container with a metal colander (I then added 170 or thereabouts water over that.)

So I took the gravity in the fermenter while it was cooling. I didn't shake it much but my top off volume was likely 1/2 a gallon.

I played around with efficiency and even by assuming that it was a 6.5G batch and a 50% efficiency, I still ended up higher.
My 1.050 was indeed at 90 degrees but temperature adjustment is fairly minimal and can't really account for .026 or greater...

We busted the thermometer in a previous brew - so we did do this by feel - but we were pretty careful with temp control (i know that my fingers can handle a 140-150 degree wort but there is distinct pain at 160 and above.) Seeing that grain is about 1/2 of the bill, I still don't think my efficiency could have been hit that bad.

 

[Ichthy]

We busted the thermometer in a previous brew - so we did do this by feel - but we were pretty careful with temp control (i know that my fingers can handle a 140-150 degree wort but there is distinct pain at 160 and above.) Seeing that grain is about 1/2 of the bill, I still don't think my efficiency could have been hit that bad.

You may have terrible conversion efficiency if you din't use a thermometer. Even a half gallon of top off water not mixed well can really effect you SG readings. Unfortunately you won't be able to put in faith in your efficiency calculations for this batch. But hey, rdwhahb, and get a thermometer for next time.

 

[Oaky]

Ok. So got a wireless thermo - that I'm using right now on a small batch. What I'm going to do is a cook up the left grains and do a gravity reading for a 1G test batch.
That way i can see if there are fermentables left (assuming that I didn't go too high in the first pass).
Never thought of the top off water as a reason why readings may be off... So you'd suggest to take an OG at pitching time then?

 

[Ichthy]

just make sure your mash temperatures are correct. Then take an OG reading before you pitch yeast. If you are doing a partial boil again you need to shake or stir the crap out of your fermenter prior to taking your OG reading so that the wort is well mixed. Don't bother with cooking any spent grains.