Low Starting Gravity

[jasonclick]

I brewed an all grain pale ale yesterday. The estimated OG should have been 1048 but when I measured it, it was at 1038 (at 68 degrees). After I completed everything, I entered it into BeerSmith and have a link to the brew sheet below. Just a summary:

9 lbs Pale Malt (2 Row) US (2.0 SRM) Grain 1 87.8 %
12.0 oz Caramel/Crystal Malt - 40L (40.0 SRM) Grain 2 7.3 %
8.0 oz Cara-Pils/Dextrine (2.0 SRM) Grain 3 4.9 %
0.50 oz Chinook [13.00 %] - Boil 80.0 min Hop 4 25.2 IBUs
0.75 oz Cascade [5.50 %] - Boil 5.0 min Hop 5 3.0 IBUs
0.75 oz Cascade [5.50 %] - Boil 0.0 min Hop 6 0.0 IBUs
1.0 pkg California Ale (White Labs #WLP001) [35.49 ml] Yeast 7 -
0.50 oz Cascade [5.50 %] - Dry Hop 14.0 Days Hop 8 0.0 IBUs

I mashed 3.5 gallons @ 152. Fly sparged 5 gallons @ 170. I ended up with 6.5 gallons in the kettle and added more water to bring it up to 7 gallons. I boiled it for 80 minutes. I ended up with about 5.5 gallons in the fermenter.

cascade pale ale brew sheet

Anyways, is there something that could have caused it to come out low?

 

[twistr25]

How well, or not, did you crush your grains? Seems like you followed the recipe, doesn't seem like you got out all of the fermentables from the mash that you were supposed to.

 

[jasonclick]

My local home brew store crushed the grains. I didn't really pay attention to how well they were crushed though.

 

[duboman]

First thing is the crush, second is your mash process. You state that you had to add water to achieve your pre-boil volume. By doing this you diluted your wort and had a lower pre-boil gravity as a result. If you did not account for this during the boil your OG is lower as a result. Basically your mash efficiency suffered. You need to tweak you equipment settings and mash volumes so you achieve your full pre-boil volume.

 

[twistr25]

Gotcha. Not saying you did(i.e I've had this happen), but sometimes when doughing in, you have to make sure as best you can to not end up with any clumps, this will reduce the efficiency of extracting the sugars. So if you had a few "doughballs" in the mash you could have missed out on some of the sugars. That seems like the most likely place to have lost out IMO.

 

[gr8shandini]

Yeah, it seems like just low efficiency from a coarse crush coupled with bypassing the grain bed with that extra gallon of water. I'm guessing you ended up short because you forgot to take grain absorption into account. The grain will soak up roughly 0.125 gallons / lb that ends up being "lost."

 

[jasonclick]

Sounds like I need to make 2 investments. A grain mill and a larger HLT. I'm using a 5 gallon water cooler for a HLT now and I'm always coming up a little short.

 

[philber]

Think about it this way, if you have 10% dissolved sugar in a gallon of water, then added another gallon of water you would have 5% sugar. Boil off 1 gallon of water you now have 10% sugar again. The sugars will not evaporate, so the additional 1/2 gal of water you added lowered the percent of sugar you had and you boiled it right back off again. So focus on the crush and the mash process to make sure you get the correct gravity and volume of water.

Play with your Mash in volume too, I find I need 3.75 gal minimum some time up to 4.5 to get 3.5 gal out on the first infusion.

Many times the LHBS grain crusher was "tweaked" by the brewer before you if it is out on the floor for anybody to access. If the LHBS does it on a non-customer system, tell them to check the setting since you had low efficiency last time. Then go out and buy your own crusher and practice.

 

[gr8shandini]

Think about it this way, if you have 10% dissolved sugar in a gallon of water, then added another gallon of water you would have 5% sugar. Boil off 1 gallon of water you now have 10% sugar again. The sugars will not evaporate, so the additional 1/2 gal of water you added lowered the percent of sugar you had and you boiled it right back off again. . .

This is true, however, if he would have added that extra gallon to the mash / sparge volume instead of directly to the kettle, he'd have likely drawn off more sugars.

 

[philber]

This is true, however, if he would have added that extra gallon to the mash / sparge volume instead of directly to the kettle, he'd have likely drawn off more sugars.

Yes! great point. The gravity would not be as high, but it is better than adding 1.00.