Strange Efficiency Difference

[k_mcarthur]

Completed my second all-grain batch last night with some strange efficiency differences from pre-boil to fermenting bucket. Was hoping someone with more experience than me may have seen this before. Followed the mash schedule per the recipe; protein rest, mash in, then two batch sparges to make 6.5 gallons. I measured the gravity and compensated for the temperature it came out to 1.042, which made for an efficiency of 76%. Then I boiled for 90 min, chilled, aerated and before adding yeast took the gravity again and it was at 1.022. How could the boil affect it that much? I'm pretty sure I read and compensated right for the pre-boil gravity, but of course can't check it again. But my Belgian witbier deffinately has an original gravity of 1.022, I guess its just going to be really really light!

 

[Gduck]

That is really odd (and a really low OG). The boil should increase the OG (boil off creates less volume, more density of sugars). Either your first measurement was wrong, or the second one was... and it would be hard to imagine your efficiency was so low you only got 1.022 as an OG. What was the grain bill like? Something just seems fishy.

 

[CastleHollow]

Assuming you did not add water post-boil, it's not possible for your gravity to be lower. Can you post up your grain schedule?

 

[k_mcarthur]

Grain bill is as follows:

4lbs Belgian Pilsner
4lbs American White Wheat
1lb Flaked Wheat
1/2lb Carapils

My first all grain was a pale ale and my original gravity on it before pitching yeast was 72%. It is very strange that this time its 37%. Since I'm just starting in all grain my equipment isn't the best but 37% is ridiculous isn't it?

 

[Gduck]

37% is pretty bad - you'd have to have forgotten to crush most of the grain or something I'd think to get that low. Have you checked to make sure your hydrometer is accurate? Put it in distilled water at 60F and it should read 1.000. I've had one where the paper tube slipped in it and my readings were wrong for a few brews before I actually checked the calibration and found it was quite off.

 

[chickypad]

As was mentioned this combo of readings isn't possible. Did you measure the second sample when hot?

 

[k_mcarthur]

Gduck I took your advice and checked out my hydrometer, you're not going to believe this. Filled my test cylinder with bottled water and dropped it in, it sank lower than the paper inside the hydrometer. I looked to see if the line on the paper still lined up with the rib in the glass that it was calibrated to, and noticed about a teaspoon of water INSIDE the hydrometer! There are no noticeable cracks or holes in the glass, but there is water inside of it. How in the h@!! could that happen? Anyway I'm sure that's the reason for the low reading and my pre-boil efficiency of 76% was probably right all along. Guess I will be buying maybe two more hydrometers to have a backup for occassions just like this. Thanks everyone for the brain storming and trouble shooting.

 

[elkshadow]

Gduck I took your advice and checked out my hydrometer, you're not going to believe this. Filled my test cylinder with bottled water and dropped it in, it sank lower than the paper inside the hydrometer. I looked to see if the line on the paper still lined up with the rib in the glass that it was calibrated to, and noticed about a teaspoon of water INSIDE the hydrometer! There are no noticeable cracks or holes in the glass, but there is water inside of it. How in the h@!! could that happen? Anyway I'm sure that's the reason for the low reading and my pre-boil efficiency of 76% was probably right all along. Guess I will be buying maybe two more hydrometers to have a backup for occassions just like this. Thanks everyone for the brain storming and trouble shooting.

Glad you got this solved!

Just a tip: Measure the OG at the temp the hydrometer is calibrated for. It's easy to get a tube full of 152 degree wort down to 68. I'm just thinking maybe the hot liquid is what broke the glass. I don't know if they are tempered glass or not.