r/Homebrewing • u/BlizardLizardWizard • May 14 '26
Help with low efficiency
Hi,
I've been brewing for a bunch of years now, but more recently started actually calculating out my efficiency for all grain brews. I've noticed that for the few I've done this for, my calculated efficiency has been unexpectedly low. I was hoping r/homebrewing might be able to help me figure out why.
As an example, my most recent recipe was a DIPA. I used 12lb pearl malt, 1lb wheat, 1lb, caramel 20L.
Mash water: 14lbs/grain x 1.4qt/lb = 4.9 gal
Water temp: 167F
I preheat my mashtun (large blue Igloo) with 175F water, which I then discard.
I add the 167F water to my mashtun and slowly stir in the grain.
Temp check reads 154F.
Steep 120 mins. Temp remains relatively stable, but at 85 mins, the temp dipped to 148, and I added 1/2 gal 175F water to bring it back up to 151F. Temp check at mashout was 149.5F.
I vorlauf and lauter, then fly sparge with 170F water to bring the pre-boil volume to 7 gal.
I measured a brix of 11.1 with a refractometer, which I converted to a gravity of 1.048.
Efficiency Calculation:
PPG = (Vpreboil x gravity points)/lbs grain = (7gal x 48)/14lbs = 24
Efficiency = PPG/PPGmax = 24/37.7 = 64%
I used table on typical malt yields in How to Brew to estimate the PPG max.
Wondering if it's the extra 1/2 gal used to temp adjust or if I'm not calculating the value correctly. Any input is appreciated.
4
u/Mattbastard750 May 14 '26
What's the gap on your mill?
My efficiency is greatly impacted by grain crush. My current mill was at .050" and I barely got 65%. My previous homebrewery had a .040" gap and even with batch sparging I still got around 80%. On my current homebrewery I knocked the gap down to .040" but I haven't brewed anything yet. I also double-geared my mill so there's no dragging of grain to get the other roller moving.
5
u/BlizardLizardWizard May 14 '26
I've been getting it pre-milled from MoreBeer.com. I don't think they specify the mill gap. But maybe investing in my own milling equipment is a next step.
6
u/Mattbastard750 May 14 '26
Yes, it is. A grain mill and a cheap 5 gal. bucket will go very far for your brewing hobby.
There's a chance Morebeer runs a wide gap to prevent people complaining about stuck sparges. My rule is to run as narrow a gap as you can and runoff as slowly as you can without constantly getting stuck sparges. If you do a wheat, add rice hulls.
I firmly recommend a mill with geared drive so both rollers spin the same. This keeps the hulls more intact for better sparging and you can run a tighter gap. The mills with one drive roller that use friction to induce the other roller to spin has a way of grinding the husk, which doesn't help.
2
u/AJ_in_SF_Bay May 15 '26
Agreed, and there is super high-quality gear out there on the cheap. I finally have a high-torque motor-driven mill that I got for about 1/4 the price of new. Facebook Marketplace can be your friend... or conversely, the enemy of your wallet. JK!
3
u/nufsenuf May 14 '26
Adjust your mash ph with some acidulated malt . I did that and my efficiency jumped a lot .
3
u/PM_me_ur_launch_code May 14 '26
Is your refractometer calibrated? Also you should figure out your correction factor.
https://www.brewersfriend.com/how-to-determine-your-refractometers-wort-correction-factor/
Even imputing 11.1 brix into the brewfather converter at 0 correction factor I'm getting 1.045. At my refractometers WCF of 1.08 it's 1.041.
Obviously this doesn't help with low efficiency but if you want to be accurate, your tools should be accurate.
I input your recipe (just grains) into brewfather under my equipment profile and I get a pbg of 1.048 with a mash efficiency of 69%.
I've tried chasing this for a while and ultimately decided just to set my equipment profile to that effeciency and correct it with extra grain. To me spending and extra dollar or two per recipe makes it easier than chasing efficiency gremlins.
Obviously if you're buying kits from more beer they have their grain mill gap set and aren't changing it. Different systems have different effeciency. So buy a couple extra pounds of base malt pre milled or buy a mill and start making your own recipes.
5
u/spoonman59 May 14 '26 edited May 14 '26
Generically, crush size can impact efficiency. Not sure how you source your grains or what you know about the crush.
Is the gravity reading after boiling? You don’t want to calculate efficiency off pre-boil gravity since boil off hasn’t happened yet.
ETA: I realize now it doesn’t matter if you calculate it prevoil. It’s simply actual gravity versus expected gravity, volume is irrelevant.
1
u/BlizardLizardWizard May 14 '26
I get my grain from MoreBeer pre-milled. Haven't invested in the equipment to do it myself.
The gravity is pre-boil. The calculation uses post-boil gravity? Interesting. In HTB, it says PPG is the "yield in terms of volume and gravity of wort collected from the mash and lauter before the boil." The equation there specifically uses pre-boil volume, though I guess it doesn't specify for the gravity.
2
u/spoonman59 May 14 '26 edited May 14 '26
Grain crush can actually matter! So consider that nothing is wrong with your process and it’s the crush.
I guess I’m wrong and it does use preboil. My mistake. I re read the equation now and it makes sense. I used brew father so don’t really calculate it myself.
How do you confirm your water volumes? I tested the volume markings in my AIO and they were off enough to cause my numbers and consistency to be off. If you have weighed or used a known accurate measure than you are good, but if your volumes aren’t what you think they are then that could impact it.
1
u/BlizardLizardWizard May 14 '26
3) is an interesting point i hadn't considered. I'll double check it. Thanks
1
1
u/Questionable_Cactus May 14 '26
You're asking about mash efficiency, so once you have extracted the sugar from the grain, that value is constant. In my calculation sheet I have that as "Gravity Points" which is PPG x volume.. This number doesn't change because it represents an absolute value of sugar dissolved (technically I think it should be "Gravity Points per Pound," but the weight of grain is fixed at this point as well so I don't care about it). After boiling, your PPG and volume both change, but the Gravity Points do not. So you are fine to calculate mash efficiency right after lautering.
Some thoughts on your efficiency: how sure are you about your refractometer? Are you allowing the wort to cool down to ~70F before measuring and also correcting for temperature calibration? Have you ever considered batch sparging, it can help with efficiency? Also, 64% is low, but not crazy low. 70% is pretty standard for most brewers, I can sometimes get into the mid-70's, but that's about it.
1
u/BlizardLizardWizard May 14 '26
The refractometer i calibrated recently so should be accurate. Im allowing it to cool to room temp before measuring.
A few people have suggested batch sparging, so that may be the next thing I try. Thanks.
1
u/PM_me_ur_launch_code May 14 '26 edited May 14 '26
There are two different types of efficiency, mash efficiency which you're describing and brewhouse efficiency, which is based off of what goes into the fermenter.
Mash efficiency is measured in the kettle and it = conversion efficiency (%) times lauter efficiency (%).
Brewhouse efficiency is measured in the fermentor and is mash efficiency (%) times your efficiency (%) in knocking out to fermentor. If you have 80% mash efficiency but only get 80% of your wort into the fermentor due to trub and other system loss, then your brewhouse efficiency is 64%.
2
u/blank-9090 May 14 '26
What is the dead space in your cooler? Could be a good chunk of sugars being left behind there. Also you vessel isn’t the best shape for sky sparging. It will be hard to evenly rinse the grains. I always got better efficiency when I batch sparged in a cooler like that.
1
u/BlizardLizardWizard May 14 '26
What do you mean by dead space? Like the tubing and stuff under the grain bed?
1
u/blank-9090 May 15 '26
Dead space is the wort that doesn’t drain. Every mash tub has some dead space. Depending on what you use for a pick up with that cooler it can be quite significant.
2
u/Indian_villager May 15 '26
As others have mentioned, there are a heap of knobs for efficiency.
1) Crush - Easily your biggest knob, Morebeer will crush a little wide so that all the newbies who didn't invest in rice hulls aren't complaining about stuck mashes.
2)Water volumes - Run your mash a little thicker, this way you move more water to the sparge volume to rinse the grains off.
3) Mash pH - I have had better efficiency by targeting 5.4-5.5 as measured at room temperature.
4) Sparge technique - There are some folks who will argue that you need to constantly maintain 1" of liquid above your grain bed. I will completely argue against this. Before you introduce your sparge water drain off wort until the very tops of the grain is peaking out, I mean barely 2mm of grain sticking out. Then while draining, fly sparge in your sparge water until you are about 1/2" above the grain bed. Stop your sparge water, and let the very top of the grain bed peek out again. From here sparge normally. What this does is to prevent what is essentially a serial dilution in that headspace above your grainbed, this way you are boosting the concentration gradient between your grain bed and your sparge water. Then once you get half of your preboil volume collected in your kettle, pause the mash tun outlet and the sparge water inlet for 3 mins. After that rest, continue sparging as normal. With all this I am still able to sparge out in 20 mins for a 5 gallon batch, and I am regularly in the upper 80s for total brewhouse efficiency.
1
u/slofella BJCP May 14 '26
I trust my refractometer to tell me that there is a ballpark amount of sugar. It's good enough because I'm homebrewing one-off batches and repeatability is low enough on the priority list that if I'm +\- 5 gravity points it doesn't matter. Heck, I've taken measurements with my refractometer within seconds of each other and they were soooo different.
If you want accurate measurements, use a hydrometer with appropriate temperature wort/beer.
Also, 64% isn't the worst.
1
u/Bottdavid Intermediate May 14 '26
I will second (or third maybe) buying a mill and crushing your own grain. It was a positive more for me on a number of things. I was able to buy grain and then not have to brew ASAP. I was able to dial it in so I get better efficiency and less stuck sparges. It's a really easy thing to do while my mash waters heating up. Relatively inexpensive too.
2
u/Ciserus May 14 '26
I ignored this for years, but it turns out pH is really damn important for brewing efficiency.
Ideal mash pH is, I think, 5.2-5.6? Turns out my tap water is above 8. Whoops.
If you don't have a way to test your pH, you might be able to look up a water quality report from your city to get an indication of how big a problem this is for you.
2
u/Olddirtybelgium May 14 '26
How fast was your lauter? Ideally you want your wort to travel from your mash tun to your kettle fairly slowly. If you crank your valve all the way open and just drain it all into the kettle quickly, you will lose efficiency.
1
u/Upset-Tangerine-9462 May 14 '26
I don't think that your efficiency is that poor. I get 71% and batch sparge with grains that I mill myself. You can spend a lot of time and energy messing with things to raise the efficiency to save maybe a pound or two of malt in a recipe. The most important metric to care about is the consistency of your efficiency from one batch to the next. If its consistent, then you can know what you'll get out of a recipe. I recommend continuing to track it before making changes. Good luck!
1
u/holy_handgrenade May 14 '26
There's a bunch of variables that all come together for mash efficiency.
Crush. The gap on your mill and the grain particle size matters. Larger gap is a larger grain size, more locked away in solid grain particles and lower resulting efficiency. Lower gap is a smaller grain size, more grain exposed to the mash to be extracted and converted. There's a point of diminishing returns; using pure flour can get you to 100% efficiency, at the expense of a stuck or extremely slow sparge. You'll need to find that sweet spot that is good for you and your equipment.
Mash thickness: You need a relatively thick mash. Too much water will dilute the enzymes and eliminate some diastatic power. That extra half gallon mid mash may have disturbed the conversion, at the very least it lowered the density of the mash which also means the gravity was also lowered making readings inaccurate at best.
Sparge: if the grain bed is sufficiently settled, has the right grain particles and husk ratios, the sparge should be a pretty reliable time to complete. Having too much water over the grain bed can increase pressure forcing water through the bed without properly washing the grains and pulling all the converted sugars from the grainbed. Too slow and it is just extra time, but if you're manually sparging, can lead to inconsistent sparging and throw the numbers off.
The goal is to find a sweet spot for what is good for you and your equipment and notating what your actual efficiency is and design recipes around that. If you have low efficiency, you'll need more grain to be consistent with expected numbers both in starting gravity, finishing gravity, and ABV. There's a danger point with having very high efficiency where you'll use less grains, but there's also less wiggle room. So a slight mess up in the crush, mash thickness, or sparge can throw your numbers off by a lot.
1
u/warboy Pro May 14 '26
Not enough data to find your problem. If you want to start trying to increase efficiency, you need more data than just preboil efficiency.
Take your conversion efficiency. This should be 95+ % unless you're using highly undermodified malts or mashing for a very short period of time. Problems here generally result from dough balls and dry spots in the mash or poorly calibrated temperature monitoring resulting in you not hitting proper saccharification temps.
Now you can look at your preboil or sparge efficiency. With a fly sparge system this is where most of your problems are. There is a direct correlation between the amount of time you sparge for and how much you are able to extract from the grain. Raising your efficiency could be as simple as lengthening your runoff process. If you're already doing a relatively long runoff, you could have channeling issues.
If you're worried about your boil off rate, you can do a post boil efficiency as well. I usually just skip this and do brewhouse efficiency. No matter what your numbers are on your past steps, you will still have a lower efficiency if you can't effectively separate trub from your wort and get it into your fermenter.
There's also one more elephant in the room. Your efficiency calculations are only as good as your data. How accurate are your water volumes really? And this is the big one I already see. Pearl malt is slightly higher kilned compared to 2 lovibond base malts. A quick google search tells me Pearl generally is somewhere between 36.8 and 38 ppg potential gravity. We as homebrewers work off malt spec sheets which are wide bands of numbers maltsters try and hit with their batches of malt. We do not have the real numbers of the malt we actually use unless you're getting a COA with your purchase.
1
u/jizzwithfizz BJCP May 15 '26
The very first thing you should be checking and adjusting is your mash pH. It is a stupid homebrewer myth that the crush is the main issue. Pro brewers measure pH all the way through a brew, and the mash pH has more effect on conversion than most other factors besides temperature. Get a pH meter and get to work.
0
u/tastygluecakes May 15 '26
I would bet a decent chunk of change that the problem is your fly sparging.
Are you going SLOOOOOWWW? If not, you should be. Otherwise you are likely just drawing lightly colored water during the sparge phase. Are you leaving 1" of water above the top of grain bed? It not, do that too.
Next brew, measure the gravity of the wort as it's coming out of the sparge every 5 minutes.
I am assuming that your mill is gapped properly. Give that a quick check to be sure.
Worst case, switch to batch sparging. It's a bit more fool proof. And don't be afraid about distributing the grain bed - add in the sparge water, stir it up, and let it settle for 5-10 minutes before taking the runnings.
1
u/BlizardLizardWizard May 15 '26
I run it quite slow with 1inch over the grain bed. Checking the gravity during the sparge is a good idea though.
7
u/dfitzger May 14 '26
Why are you mashing for 120 mins? Most conversion is happening in the first 15mins.
The extra 1/2 gallon in a 7 gallon batch will throw the numbers off for sure.