I read the thread on mash efficiency and found it very interesting. I aim for 70% efficiency but I rarely seem to hit it. More often than not I’m in the high 60s. Yesterday, I brewed an amber ale. My mash water temp was a bit high to start at around 158F, but I left the lid off and did a bit of stirring and after 20 minutes it dropped down to 152F. When I added the sparge water, the temp was 170F. When I took a pre-boil reading, my gravity was 1.039, which was only a point off the 1.040 I was aiming for. I did a slightly longer boil than the usual 60 minutes hoping to gain that point back. My post-boil gravity was 1.048 instead of the 1.050 I was aiming for.
I’m brewing 2.5 gallon batches and I use a 5 gallon Igloo water cooler for a mash tun. When I was cleaning up, I filled the cooler with cold water to cool the grains down. Just on a whim, I got the hydrometer out and took a reading of the cold grain mix. I got a reading of 1.004.
Here is my question. I realize I’m not ging to get ALL the sugars out of the grains, but I was kind of surprised there was still that much sugar left. Or, would that be a ‘normal reading’ and I’m seeing a problem where none exist?
If anyone has any insights, I would be grateful. Thanks.
The two major parts of brewhouse efficiency are mash/conversion efficiency and lauter/extraction efficiency. if you carefully measure your grain and your strike water you can use tools on line to calculate a pretty accurate estimation of your mash efficiency. this is where the crush comes in, if that is good you should be pretty close to 100% mash efficiency. The Lauter efficiency will not be close to 100%, well, it might be but not AS close. What you are seeing is the difference between mash efficiency and lauter efficiency. 1.004 is not usual. pretty low actually.
Ah, very interesting. On the plus side, if I’m understanding you, I’m doing a good job with my mash, getting most of the sugars out. On the minus side, that’s telling me that my crush needs to be better. It would also explain why every once in a while, I’ll have a batch where I get great efficiency. I don’t have access to a mill except at the local supply shop so I’m kind of stuck there. Thanks.
I would ask your LHBS to double crush your grain for you. It made my efficiency much better and more consistent.
How much grain did you use, and what were the volumes? If the tail runnings are 1.004 your efficiency should be very high.
I’m doing 2.5 gallon batches. Total grain bill was 5.25#. Mashed with 2.25 gal & sparged w/ 2.5 gal.
+1 to double crushing the grain. Other things to consider… Are you hitting your post boil gravity. You said you’re going 2.5 gal batches. Is your volume 2.5 when dine or is it 2.75 or 3? Also check the accuracy of your hydrometer. Sometimes the paper in those things get shifter around
Given what I’m reading here about that 1.004 reading, and that was my big question, I’m pretty sure any efficiency problems are the grind on the grains. Because that’s the thing, I’m not hitting my post boil gravity in most cases. As far as the other things to consider, my post-boil volume was a little over 2 3/4 and volume in the fermenter was about 2 2/3. When I bottle, I’ll have about 2.5 gallons. In regards to the hydrometer, it doesn’t get used that much. I was able to find a refractometer on amazon for a decent price and that gets the bulk of use.
I’ve been wondering about the crush for a while and this just reenforces that concern.
Something has to be off with these numbers. 5.25 lb of grain would absorb ~0.6 gal, leaving a pre-boil volume of ~4.1 gal. To concentrate that from 1.039 to 1.048, you’d end up with 3.3 gal post-boil and your efficiency is around 80%.
Or you’re starting with ~3.1 gal in the kettle, boiling down to 2.5 gal, and your efficiency is low because you have a huge amount of dead space, around a gallon.
Edit: OK, ending up with 2.8 gal and assuming the gravity measurements are accurate, you’d have to start with around 3.5 gal, and that’s still a lot of dead space (~0.6 gal).
Regardless, the next step is to calibrate your instruments and take a complete set of volume/gravity measurements next time. Then you can figure out where your losses are coming from.
I used to have that highly variable efficiency problem. Finer crush was probably the number one fix. Looser mash (went from 1.25 lbs/qt to 1.5 lbs/qt) was probably the number two fix because mixing became easier and better. Mash pH was probably number three.
+1. I worked on all of those too. Took care of the variability.
Well, before my next batch, I’ll take a look at my kettle. A good while ago, I measured out a gallon and added it to the kettle. The volume in the kettle matched the 1 gallon mark ON the kettle and I think I measured out a second gallon. When that matched, I assumed the rest of the markings on the kettle were correct. When I put the kettle on the stove, I had wort that was just below the 4 gallon mark. After a 65-70 minute boil, when I took the IC out of the kettle, I was under 3 gallons.
If you are calculating your recipes at 70% efficiency for 2.5 gallons and you’re ending up with 2.75-3 gallons post boil, your gravity will be slightly lower than expected. You will lose beer when transferring, but what you lose is gone. The goodness of that wort doesn’t carry over. When I brew 5 gallon batches, I calculate my recipes as 5.5 gallons so I can account for the loss in transferring and bottling. My 10 gallon batches get measured as 11 gallon batches.
I got a reading of 1.004.
Here is my question. I realize I’m not ging to get ALL the sugars out of the grains, but I was kind of surprised there was still that much sugar left. Or, would that be a ‘normal reading’ and I’m seeing a problem where none exist?
If anyone has any insights, I would be grateful. Thanks.
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1.004 is quite low in my eyes especially if your brewing light lagers. Also i believe that reading taken from an unknown amount of water placed into the mash ton, cold doesnt really give you an accurate measurement. Also in my experience a refractometer isnt very accurate for multiple reasons. Stick with a good old hydrometer (calibrated to suggest temp in RO or distilled water). There are so many factors effecting “brewhouse efficiency”. It doesnt seem like you have any concerning issues. For me i want consistency every single time so i have learned to control/manipulate every aspect of the process possible to give me my desired tasty beverage:) This is some light reading from a well known site. Troubleshooting Brewhouse Efficiency - German brewing and more
There is a trouble shooting spreadsheet in there somewhere. It allows you to break down/ separate your conversion efficiency and lauter efficiency.
Hope this helps somewhat i feel like i got off on a tangent a bit:)
How are you measuring your preboil Gravity? IF you are using a hydrometer are you cooling the wort down to room temp or are you correcting for the heat? Ive read that correcting for gravity can be off a certain percentage? Also id calibrate your hydrometer and thermometer.
I’m brewing 2.5 gallon batches and I use a 5 gallon Igloo water cooler for a mash tun. When I was cleaning up, I filled the cooler with cold water to cool the grains down. Just on a whim, I got the hydrometer out and took a reading of the cold grain mix. I got a reading of 1.004.
Here is my question. I realize I’m not ging to get ALL the sugars out of the grains, but I was kind of surprised there was still that much sugar left. Or, would that be a ‘normal reading’ and I’m seeing a problem where none exist?
If anyone has any insights, I would be grateful. Thanks.
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Regarding your question about gravity after mixing water with the spent grains; if you filled the cooler with water, I would guess that’s a pretty high reading as you must have diluted the grains with maybe 2 or 3 gallons of water. That said, it is common to take gravity readings toward the end of the sparge (undiluted runnings). The final runnings should not be allowed to go below 1.008 as below this point tannins can be extracted from the grains creating astringency. Above this point you are loosing efficiency. A few points higher will not have much effect on efficiency but in my experience with light Belgians, lower will create astringency. I try to stop my sparge anywhere between 1.012 and 1.008. Also, the pH of your final runnings should be below 6.0 to avoid astringency.
The title of this thread sounds like we are breaking up.
We are. But it’s nothing you did. Really. I hope we can remain friends.
It’s not you, it’s me. 
No, no, it was ALL me. On my most recent batch, I got a double crush on the grains where I hit the pre-boil gravity and missed the post-boil/starting gravity number by just .001. I’m happy. Thanks all.