Low efficiency or bad hydrometer reading?

[RunCMC]

Just finished brewing an imperial ipa, and my og reading is way off...my software says that at 65% efficiency my og should be 1.078, my actual reading is 1.040... This puts me at 35% efficiency?!

Recipe was 16lbs 2-row, and 2 lbs crystal 20

How could my efficiency be so low? Hit mash temp spot on at 152, mashed for 75 minutes, and did successful conversion test with iodine. Wort was aerated and sample was taken right before pitching yeast.

Any ideas? Is my hydrometer broken, our am I?

 

[helibrewer]

Unless something is making your hydrometer a lot heavier than it should be, something is a miss.

What was the wort temp when you took the gravity reading? I assume this is a 5 gallon batch? I also assume this is a full boil since it was all grain?

Sounds like a reading when the wort was still very hot since the density is lower.

 

[dbhokie]

It does sound like Temperature, it could be also settling of the wort if the sample wasn't from well-mixed wort, but I highly doubt it would throw it that much. I've never had that much of a disparity unless it was temperature.

You can check your hydrometer, measure it with water, and then suspend some table sugar in a certain volume and figure out what your gravity should be. 46 points per pound on sucrose.

 

[RunCMC]

Temp was 80... It was a full boil, I'll have to check the hydrometer with water and sugar. Thanks for the quick responses!

 

[helibrewer]

Has your hydrometer and thermometer been used successfully in the past? You might double check your thermo in freezing and boiling water to get those data points.

 

[dbhokie]

80 F? That would make it more like 1.042, are you sure that you read the hydrometer correctly? (Didn't accidentally read another number like plato? Even then that would have put you at 18-21 probably. If you kept 153 temp for an hour with that much 2 row, there has to be another variable missing. Did you crush your grains at all?

Not trying to be insulting, just checking!

 

[RunCMC]

Grains were crushed by my LHBS which I've used on several occasions now with no issues. Plus the iodine test showed conversion.

 

[Jayhem]

I suspect either grain crush or wort that wasn't fully mixed when you drew your sample.

When I used to have the brew store mill my grain I was getting 50% efficiency! Now that I mill my own I get 70-80%!

 

[dbhokie]

Grains were crushed by my LHBS which I've used on several occasions now with no issues. Plus the iodine test showed conversion.

That'd confuse the hell out of me.

I'd take a half gallon of water
Mix with a half pound of sucrose table sugar.
Suspend well, maybe warm a bit to get it suspended well.

OG should be around 1.040-1.05 (depending on measurement accuracy, evaporation, and final volume)

I mean the only things I have encountered to hinder efficiency drastically were:

Grain Crush
Temperature
Sample not well mixed
Pre-Boil confusions, and saccharide addition confusion
Mash ph

 

[Jayhem]

I suspect either grain crush or wort that wasn't fully mixed when you drew your sample.

When I used to have the brew store mill my grain I was getting 50% efficiency! Now that I mill my own I get 70-80%!