Stuck on efficiency

[jdecker1978]

So I know this is covered all over this forum, and the rest of the web. But I have read, and read, and read, and can't fix my problem. I am stuck brewing around 60-65%. I increased grain for a while, but really want to try and button it down. I've been brewing about two and a half years, about seven or eight months with my current setup.

15 gallon coors keggle with sight glass and thermometer
48qt coleman rectangular cooler w/stainless braid

Heres my method-
Put all the water in keg
Heat water to around 167, let gravity add Beersmiths quantity to cooler. Close and let heat for 5 min.
Add grain and stir to get a temp of 152.
Let sit for 75 minutes (used to do 60 but some folks said this could help). After my temp is around 148.
Vorlauf a gallon.
Drain tun into bucket.
Add 170 degree water (typically I would split the remaining water and do this twice, but I'll get more into that below). Stir and let sit 10 min.
Vorlauf another gallon.
Drain. Despite what people say, the slower I drain my efficiency goes up a hair. I constantly read in batch sparging that doesn't matter.
I use a bucket because the keg still has sparge water.
When all the water is through I transfer back to keggle, boil, and theres my beer.

Pretty sure my problem is in the mash/sparge as I've checked pre boil OG and it was off. Until recently I was not super accurate with my equipment profile, but this last brew I really got into it and nothing changed. A couple things I thought would help were-
A)checking the "drain mash tun completely" box in beer smith mash profile
B)checked "adjust mash for deadspace"

Previous to today I was using a med body batch sparge profile in beersmith and simply splitting the second addition of water into two. I know this was wrong. I know now that the point is two equal drains, not equal amounts of sparge water. So I measured my deadspace, checked the box did a single batch sparge, and my drain was a half gallon over what Beersmith expected it to be(my deadspace is a half gallon as well). But I'm not sure a half gallon would even make a 10% difference in efficiency.

Im pretty sure the crush is fine. I know someone who uses the same supplier and mill, and does fine. In fact, last week we brewed together and got 78% with his rig. The only real difference is he just got a keggle mash tun. But I don't see how that would effect it either. He hasn't used his new setup enough to know if he's got a consistent efficiency.

I brew 6.5 gallon batches, so I don't need to be greedy with transfers and can still fill a corny to the top at the end of the cycle.

Please let me know if theres any more info anyone needs to hopefully help me fix this nightmare!!!

Thanks in advance.....

 

[stpug]

A grainbill example with volumes and gravities would give me/us something to work from. Also, are we talking about mash efficiency or brewhouse efficiency (if brewhouse, are you talking boil kettle or fermenter?).

One bit that catches my eye is: "I brew 6.5 gallon batches, so I don't need to be greedy with transfers and can still fill a corny to the top at the end of the cycle."

That's a fair amount of loss (1.5 gallons) from batch size to corny. Some of that would definitely be lost from BK to fermenter which affects efficiency in a program like Beersmith.

BUT... the most helpful would be recipe grainbill and volume/gravities (preboil, postboil, fermenter).

 

[billl]

If you get higher efficiency when draining slowly, then that is a good indication you aren't stirring hard enough. That is a pretty easy fix to gain a couple points. Also, remember to tip the tun to get the last bits out for the first runnings.


The rest is going to take a bit of troubleshooting and measuring.

Step 1 - calibrate everything - thermometer, hydrometer, volume measurements etc.

Step 2 - measure every step in the process for volumes and gravity.

That will narrow down where the problem is. Braukaiser has a great writeup on how to measure your mash.

http://braukaiser.com/wiki/index.php?title=Understanding_Efficiency

The really critical thing to verify is that you are getting 100% conversion. If you scroll down a page or 2 on that link, there is a chart showing maximum gravity for a given mash thickness. eg 1.24 quarts/lb should give a maximum gravity in the mash of 1.096. If you take a gravity reading and get something less, you've found the issue.

With your efficiency levels, that is probably going to be most of the problem. Once you verify that is the issue, there are only a few things it can be. The #1 culprit is crush. #2 is improper PH. I know you don't think its the crush, but a finer crush will fix a lot of other minor problems.

If you are getting 100% conversion, then the problem is in draining or sparging. Check the volume of the 1st runnings. It should be about 1/8 gallon less than your mash in volume for each pound of grain. eg 12 lbs should absorb about 1.5 gallons. If you are missing more water than that, then you'll want to use some rice hulls or something to get it draining better.

 

[DWBoca]

I have the same mash tun. I started using a copper manifold instead of the stainless braid. My efficiency went up. I also started to stir the mash every 20 min or so.

 

[acidrain]

Are you talking mash efficiency, or brewhouse efficiency?
Do you have trub and equipment losses?
How did you calibrate your volumes?
Did you and your buddy use two different thermometers?
What do you use to measure gravity? Is it calibrated?
If you use a hydrometer, do you let the sample cool?
What gravity do your beers typically finish?

 

[b-boy]

Sounds like equipment profile to me. Look at your settings in BeerSmith and then verify that they match what's going on in your system. Things like boil-off and losses due to equipment. Recently, I had problems when I switched from my round cooler to a rectangular cooler. My efficiency dropped quite a bit. I'm still trying to figure it all out.

Other than that I'd say crush. Why not have your LHBS run the grain through their mill twice and see if you see any improvement.

 

[b-boy]

I have the same mash tun. I started using a copper manifold instead of the stainless braid. My efficiency went up. I also started to stir the mash every 20 min or so.

That's interesting...My rectangular cooler has a stainless braid. My round cooler uses a manifold. Hmm... The rectangular cooler drains much faster, but my efficiency is lower.

 

[DWBoca]

That's interesting...My rectangular cooler has a stainless braid. My round cooler uses a manifold. Hmm... The rectangular cooler drains much faster, but my efficiency is lower.

My efficiency has approached 82-85% I got my ideas from how to brew by John Palmer

 

[jdecker1978]

Thanks so much everyone!

First off-I think its mash efficiency. I don't typically measure pre boil OG, but I have and it was low. I did not today. My grain bill was 15 lb 2row, 1.5 lb crystal 30L. I ended up with 1.056, as opposed to the 1.068 I was shooting for.

Beer smith called for 5.8 gallons for mash in. with 16.5 lb grain. I got 4.2 gallons out of that. It called for another 5.4 gallons for sparge. I got 4.75 back from that for a total of 9 gallons of wort.

I lost .6 gallons with a 16.5 lb grain bill in my first runnings. So thats a little off.

I calibrated my thermometer and hydrometer several months ago, and still had the problem then. I will re do that before the next brew. My friend and I did not use the same thermometer.

My equipment profile seems good, though I really wish I would have checked the pre boil OG today. I assume thats a good practice to know if the issue is with the mash....

I've never looked into the ph before. I will check that article.

And several of the changes I made were to match what John Palmer describes in his batch sparging Youtube video.

 

[jdecker1978]

Sorry Im new to writing in these forums, and may have made a confusing reply with not specifying answers. After rereading, a couple things I missed-
I stir it pretty hard, but have never tipped the tun. If I tip the tun, should I uncheck the "deadspace" box to take that extra half gallon of water out of the mix?

Volumes are measured in a pitcher, and with sight glass(that I need to double check)
As far as the hydrometer, I checked it with water a few months ago but that was it.
Also, at my LBHS you run the grain yourself. Been doing it twice for a while.

I kind of wing it when I brew so bear with me. Im not fluent on all the terms etc... so sorry if Im not making any sense. Thanks for bearing with me.

 

[acidrain]

Some things I was eluding to...
Mash efficiency is what you should be calculating... it's the total volume (pre-boil) and specific gravity. You can enter those into BS and see what you mash efficiency is.
Trub left behind after boiling, loss to hops absorption (leaf hops?), equipment losses, etc. all affect the final brewhouse (BH) efficiency.
Brewhouse efficiency is always lower, and 60 or 65% BH efficiency isn't that bad.
I get 75-80% Mash efficiency, but only 60-65% brewhouse efficiency because I use leaf hops and choose to leave quite a bit of trub behind.
If your measurements are off (volumes, temps, or gravity) you won't be calculating correctly.
If your thermometer is off, and you mash higher than thought, you will have less fermentables, and your final gravity will be kind of high (is it more than 1.015 or so?).
If you are not cooling your samples before measuring, they will be off, even if you calculate the temperature variable. With a hydrometer, you have to measure the temp of the sample, and match it to your hydrometer's calibrated temp (it will be written on the hydrometer).
Equipment aside, the one biggest factor in mash efficiency is the crush. All of the husks should be crushed with the hulls split open and empty, but left mostly intact, and the kernel broken into smaller pieces. Are there any intact kernels after crushing?
After that it is probably water profile.
Have you tested, or do you know your water profile? Might want to try using RO or distilled water fortified with gypsum and calcium chloride. See the water primer here: https://www.homebrewtalk.com/f128/brewing-water-chemistry-primer-198460/

 

[OleGoatBrewing]

Sounds like equipment profile to me. Look at your settings in BeerSmith and then verify that they match what's going on in your system. Things like boil-off and losses due to equipment. Recently, I had problems when I switched from my round cooler to a rectangular cooler. My efficiency dropped quite a bit. I'm still trying to figure it all out.

Other than that I'd say crush. Why not have your LHBS run the grain through their mill twice and see if you see any improvement.

Agree with both of these comments. It's the best place to start. Also, take 5 gal & run it though your process. Measure out what you have at the end. Once you get a good equipment profile (using BeerSmith) you'll hit your numbers all the time. I tell my brother-in-law what the numbers are before we take measurements...he thinks I have some voodoo magic brewing skillz! Which I do...:rockin::rockin:

Good luck!

 

[jdecker1978]

Thanks guys. I really wanted to see if there was a big red flag somewhere with my process. I'll go over the info I got today, and maybe brew another batch this weekend for some more tests.

Thanks again!

 

[billl]

"Beer smith called for 5.8 gallons for mash in. with 16.5 lb grain. I got 4.2 gallons out of that. It called for another 5.4 gallons for sparge. I got 4.75 back from that for a total of 9 gallons of wort. "

That's a red flag for me. 16.5lbs of grain should absorb about 2 gallons of liquid. Your calculations show a loss of only 1.6 gallons for both dead space and grain absorptions. That is a pretty good indication that the water isn't really reaching everything in the grain. I suspect if you measure the gravity of the mash itself (before running anything off), you will find is well below the maximum.

Also, the sparge step should have the volume collected equal to the sparge volume added. The grains should already be holding as much water as they can, so you are essentially just washing some of that sugar laden water out with new, fresh water. You lost 0.65 gallons in that step - which happens to be about the same amount of water that should have been absorbed by the grain in the original mash.

So, my best guess would be that you really aren't getting water in to the center of the grain well enough to get all the sugar out. The easiest solution to that is to just mill a bit finer so the pieces are smaller. Also, make sure you really mash in well and consider stirring well a couple times during the mash.

 

[Redhawk96]

I had similar issues when I switched to a bigger rectangular cooler from a round cooler. The two main things that helped me get back to where I was before:

1. Stir the mash like it owes you money. We got a bigger mash paddle that moves it around more efficiently, and stir once mid-mash, as well as right befor we vorleuf.
2. Mash for 75 minutes instead of 60.

 

[masampson]

I'm also pretty new to writing in here but I pretty much use it for any question about anything I ever have. I'm by all accounts a newbie myself, having only been brewing for a few years.

You said at the start that you are adding 170F water to your mash out? Since the target is to "loosen up" the mash and dissolve the sugars by getting the mash as close to 170 as possible, adding 170F water might not get you there since it's mixing with the cooler grains. If the sugars aren't getting loose enough, that could be a factor for you..

I hadn't really been taking pre-boil grav readings either until recently, but it really is necessary if you want to know your mash efficiency. If you're using BeerSmith there is a hydrometer temperature adjustment calculator in the Tools if you are using hot wort.

I don't have any super fancy equipment yet for reading mash pH yet, so I use litmus papers. I know they aren't exact, but they are cheap and at least would tell you if you are way off for some reason. Also, it wouldn't hurt to pick up a small bottle of some iodine to test your starch conversion. Pretty easy to use and also relatively cheap.

 

[acidrain]

If you're using BeerSmith there is a hydrometer temperature adjustment calculator in the Tools if you are using hot wort.

Unless your temp is very close to the calibrated temp (withing 20 or 30 deg) this isn't accurate.
Anything over 80 or 90 deg and you will not get an accurate measurement even using conversion tables.

 

[feinbera]

Can you talk about your "add grain" process? I think bill is onto something – the high volume of first runnings and significant absorption of sparge water would seem to indicate that the mash water isn't getting everywhere it needs to be, but it could be an issue of mixing rather than crush.

If you're dumping all your grain quickly in, you could have big dry pockets, especially around the corners/edges of a big rectangular mash tun. My process is to have a brew buddy slowly pour the grain in over a period of a minute or two while I furiously stir at the spot where the grain's meeting the water, then throw in a like-it-owes-me-money stir for good measure every 20 minutes in a 60 minute mash, and I routinely get 70%-75% efficiency with a default LHBS crush and not even trying to worry about PH.

 

[jdecker1978]

Wow so much info!

Im going to get all the accurate info into beersmith, and calibrate everything/check volumes first.
My buddy went over my profile and adjusted it which ended up with much less water needed, though I haven't had a chance to look at that yet.
When I add grain, I dump about half, then stir, then dump the other half. Im using a large spoon and have been planning on switching to a paddle so I'll do that too and really stir the crap out of it. I don't know if the numbers are standard, but the mill at my LBHS, they say run it at 40 then again at 25. It used to just be 35 but they said they were getting efficiency complaints. The brew my friend and I did last week used the same mill, and came out fine.

When calculating water should the deadspace box be checked in beer smith?

 

[acidrain]

Dead space is wort you will never get.
If you are tipping the kettle, or doing whatever you need to get all the wort out, then no, uncheck that box.
If you are leaving wort behind for whatever reason, carefully measure what that amount is, enter into beersmith, and then check the box. It will make your batch that much bigger.

 

[b-boy]

Im using a large spoon and have been planning on switching to a paddle so I'll do that too and really stir the crap out of it.

You really need a paddle and you need to stir the hell out of your mash. A spoon definitely won't do it.

 

[muels]

"Beer smith called for 5.8 gallons for mash in. with 16.5 lb grain. I got 4.2 gallons out of that. It called for another 5.4 gallons for sparge. I got 4.75 back from that for a total of 9 gallons of wort. "



That's a red flag for me. 16.5lbs of grain should absorb about 2 gallons of liquid. Your calculations show a loss of only 1.6 gallons for both dead space and grain absorptions. That is a pretty good indication that the water isn't really reaching everything in the grain. I suspect if you measure the gravity of the mash itself (before running anything off), you will find is well below the maximum.



Also, the sparge step should have the volume collected equal to the sparge volume added. The grains should already be holding as much water as they can, so you are essentially just washing some of that sugar laden water out with new, fresh water. You lost 0.65 gallons in that step - which happens to be about the same amount of water that should have been absorbed by the grain in the original mash.



So, my best guess would be that you really aren't getting water in to the center of the grain well enough to get all the sugar out. The easiest solution to that is to just mill a bit finer so the pieces are smaller. Also, make sure you really mash in well and consider stirring well a couple times during the mash.

I agree with Bill... Your absorption rate is off somewhere. Using my rate (.135) I would get about 3.5 gallons out. Either the crush is coarse, you are not doughing in properly, or you are not mixing well enough after dough in.





Sent from my iPad using Home Brew

 

[brewing_clown]

Had a similar issue last year. Narrowed it down to my thermometer being 2 degrees off. I bought a thermapen, and the problem went away.

 

[stpug]

I use a spoon for stirring. No problem with efficiencies.

 

[jdecker1978]

Well its been a while...and several brews. I brewed with a couple friends (fly sparging, 3 keggles) and hit 86% with one and 78% with another.

After all the info from the last few brews, today was the big test. Thermometer was off, profile was off. Fixed them both. Yet today we brewed 63%.

My temps were right on, we stirred the hell out of it (still with a spoon), and batch sparged. Ended up with a little more wort than beersmith called for (1 qt), so I boiled an extra 15 minutes and burned it off.

The grain bill was 14 lb 2row, 1.5 lb crystal 30. I started with 5.5 gallons, drained 3.75 out of that. Added 4.5 more for the batch sparge, drained 4.25 out of that. My brew buddy who knows much more than I do came over and went over everything with me. Measuring temps in different part of mash, everything. And he was shocked.

Why why why?

 

[jdecker1978]

And I will grind finer next time...

My friend and I use the same settings on the mill and he gets 78%...

 

[madscientist451]

What was the pre boil gravity? You say you stirred the mash? When did you stir it?
What was the mash temp after stirring? Did you stir the batch sparge?
What was the gravity of runnings at the end of the batch sparge?

 

[gundarak]

http://braukaiser.com/wiki/index.php?title=Understanding_Efficiency

This is amazing, finally something that clicks with my brain. im going to read the hell out of this site! Thanks!

 

[GoCobbers95]

Can someone explain how you can stir your mash vigorously and often, while still keeping your mash temps where you want them in a standard igloo style cooler.

Lot of solid info in the thread! Thank you all!

 

[stpug]

Can someone explain how you can stir your mash vigorously and often, while still keeping your mash temps where you want them in a standard igloo style cooler.

Lot of solid info in the thread! Thank you all!

I don't think that it's needed to stir often and vigorous, BUT if you want to and maintain your mash temps and stir often (every 10 minutes or so) then simply keep a small amount of water at near-boil on your stove. Every time you open your MLT to stir, add in a cup or two of the near-boiling water to refresh your temps. I will generally stir and refresh my MLT once at the midpoint and use about 0.75-1 quart of boiling water in a full 5 gallon grainbill. This works very well and keeps my STIRRED mash within about 1 degree variance of my mash temp.

 

[fatom99]

What temp do you mash out at? 170 degree sparge water seems low, since you want to raise the mash temp 168 degrees. I heat my sparge water to 178 to bring my mash temp to 168; of course the sparge water temperature is dependent on the sparge water volume and the mash temp.

 

[doug293cz]

Well its been a while...and several brews. I brewed with a couple friends (fly sparging, 3 keggles) and hit 86% with one and 78% with another.

After all the info from the last few brews, today was the big test. Thermometer was off, profile was off. Fixed them both. Yet today we brewed 63%.

My temps were right on, we stirred the hell out of it (still with a spoon), and batch sparged. Ended up with a little more wort than beersmith called for (1 qt), so I boiled an extra 15 minutes and burned it off.

The grain bill was 14 lb 2row, 1.5 lb crystal 30. I started with 5.5 gallons, drained 3.75 out of that. Added 4.5 more for the batch sparge, drained 4.25 out of that. My brew buddy who knows much more than I do came over and went over everything with me. Measuring temps in different part of mash, everything. And he was shocked.

Why why why?

Put a couple of gallons of water in your MLT, and then drain exactly the same way you do when running off wort. Then dump the water remaining in the MLT after draining into a measuring cup large enough to hold it all. How much water was left in the MLT? This is your MLT dead volume. A high dead volume can adversely affect your mash efficiency (actually the lautering efficiency.) You want the MLT dead volume to be a close to 0 as possible.

You can also measure the SG of your first runnings, and then multiply the SG points [ (SG-1) * 1000 ] times the strike volume you used in gallons. This number should be close to 558 (which should be close to the total potential points of your grain bill.) If it's significantly lower, then you have a problem with your conversion efficiency (not converting the max amount of starch to sugar.)

Mash efficiency = conversion efficiency * lauter efficiency.

Brew on

 

[estricklin]

First off, get yourself a GOOD false bottom. Buy one, or make one from an aluminum pizza pan or a stainless steel element cover for an electric stove. I just read through and I think I read that you have a stainless braid? Batch sparging helps to overcome having a poor false bottom, but I believe that a few bucks on a good false bottom is money WELL spent in homebrewing.

You've been suspecting sparging slower makes a difference, so slow down even more! I have both batch and fly sparged over the years, and I find that sparging too fast in either setup causes my efficiency to suffer, although it's more so in the fly sparging.

Something no one has mentioned much, is your evaporation rate. How can that possibly have an effect on extracted sugars/starches from the mash? Simple, the more water you use, the more sugars you'll extract. Beersmith calculates everything based on the amount of wort you want when the flame is out. Obviously this may not be something you can change, or can change easily; but I mentioned it on the off chance that you might be boiling at a low rate, as in your wort is just barely boiling.

Some things that have been mentioned but I will reiterate, make sure your sparge water temperature is in that 170-175 range, a higher temperature will help the sugars/starches to dissolve easier. Be sure to calculate your volumes as accurately as you can. Crush finer....hell crush til your scared!

Do not confuse starch conversion and sugar/starch extraction. The hydrometer doesn't discriminate, it measures sugars AND starches, so if your mash conversion wasn't complete it won't matter as far as extraction goes, and THAT is what we're really talking about here. Mash pH, temperature, and recipe have virtually no effect on your extraction.

To sum it up really; I bet ya 2 crawdeads and a dollar if you crush finer and sparge slower, you'll be happy with the result!

 

[jdecker1978]

Thanks everyone.

My preboil gravity was 1.050. One thing I know we screwed up was the sparge temp. Beer smith just said 168, and I thought that meant 168 degree water to bring the mash back to 152, where I mash. I know now this means bring it back up to 168. I don't know the batch running OG, I combine them right away with the original runoff, getting me the 1.050.
Another error I made was when I originally calculated my dead space, I didn't account for the grain. When there is grain in the bottom of my cooler, pretty much all of the wort drains out. This means I mashed with too much water.
I don't want to use a false bottom if I don't have to. Everything I'm basically doing is the dennybrew concept. I have pretty much the exact same tun as him, and he brews mid 80% regularly. An interesting thing is he suggests draining the tun wide open. He says from his initial mash drain to the end of the sparge drain is 15 min max.
I will crush finer next time. With the adjustment in dead space, my sparge will be much close to half of the total runnings, which it seems is what I want. I'll give it another run next week and see how it goes.
Thanks again.

 

[doug293cz]

You don't have to sparge with hot water. Kai did an experiment comparing hot and cold sparge water (http://braukaiser.com/blog/blog/2009/05/12/cold-water-sparging/), and found the efficiencies were the same within experimental error. You can also drain the wort as fast as your MLT will allow when batch sparging. Once the sugar is fully dissolved in the wort, running off slower won't dissolve any more sugar as the wort and grains are in equilibrium. If your mash is long enough, the sugar will be in equilibrium. If you mash is not long enough, then you are not in equilibrium (and conversion may not be complete either), and in that case longer run off times can help more sugar dissolve.

A lot of the processes during the mash are controlled by diffusion: water into the grain, sugar and soluble starch out of the grain, etc. Smaller grain particles provide for shorter diffusion distances, so things happen faster. This can improve your conversion efficiency for a fixed mash time, and even allow a shorter mash with good conversion if the crush is fine enough. With very large particles, the diffusion processes may not complete before the end of the mash, in which case your efficiency will suffer.

Brew on

 

[jdecker1978]

I only batch sparge. Its odd because if the sparge temp doesn't matter, then I'm brewing low 60%'s strictly because of small miscalculation with dead space, and grain crush? That seems odd because we crush the grain the same when brewing on my friends rig and get 78-79% (though we fly sparge with his setup). Not saying your wrong, just seems odd.

 

[jdecker1978]

I forgot to mention estricklin I boil pretty hard.

I really want to thank all of you again for chiming in. But you must understand how frustrating this is. I've brewed a ton of beer. I just never cared before. Now that I want consistency this is driving me nuts. Its really hard with the brewing community constantly telling me the opposite of the last guy. One of you says sparge temp is very important, one says its not.
I think my next step is following denny's system exactly, seeing as he has the identical tun and sweats by it. I WILL crush finer next time as well.
At least all the beer I make in my trials still tastes awesome. Probably nearing 50 batches and they've all been incredibly delicious. And thats all that really matters(well that and having fun brewing!).

 

[doug293cz]

I really want to thank all of you again for chiming in. But you must understand how frustrating this is. I've brewed a ton of beer. I just never cared before. Now that I want consistency this is driving me nuts. Its really hard with the brewing community constantly telling me the opposite of the last guy. One of you says sparge temp is very important, one says its not.

I understand your frustration. There is a lot of conflicting information out there. I chose to believe the results of documented experiments, where I have a pretty good understanding of what was done, and the limitations of the experiment. I also choose to believe that which is consistent with fundamental scientific principles (as I understand them.) You have to decide for yourself what information you trust. If you can find a few people with demonstrated knowledge and consistent correctness, that can make your brewing life simpler. Good luck.

Brew on

 

[billl]

You don't have to sparge with hot water. Kai did an experiment comparing hot and cold sparge water (http://braukaiser.com/blog/blog/2009/05/12/cold-water-sparging/), and found the efficiencies were the same within experimental error. You can also drain the wort as fast as your MLT will allow when batch sparging. Once the sugar is fully dissolved in the wort, running off slower won't dissolve any more sugar as the wort and grains are in equilibrium. If your mash is long enough, the sugar will be in equilibrium. If you mash is not long enough, then you are not in equilibrium (and conversion may not be complete either), and in that case longer run off times can help more sugar dissolve.

A lot of the processes during the mash are controlled by diffusion: water into the grain, sugar and soluble starch out of the grain, etc. Smaller grain particles provide for shorter diffusion distances, so things happen faster. This can improve your conversion efficiency for a fixed mash time, and even allow a shorter mash with good conversion if the crush is fine enough. With very large particles, the diffusion processes may not complete before the end of the mash, in which case your efficiency will suffer.

Brew on

Just a note on the numbers there. The "hot" sparge went from 98% conversion efficiency to 89% into the kettle. 9% of the sugar was left in the mash tun. The "cold" sparge went from 99% to 86% into the kettle. 13% of the sugar was left in the mash tun. I don't know what the total error margin was in that experiment, but a variance of 4% is larger than most of us see from batch to batch.

 

[doug293cz]

Just a note on the numbers there. The "hot" sparge went from 98% conversion efficiency to 89% into the kettle. 9% of the sugar was left in the mash tun. The "cold" sparge went from 99% to 86% into the kettle. 13% of the sugar was left in the mash tun. I don't know what the total error margin was in that experiment, but a variance of 4% is larger than most of us see from batch to batch.

If you look at the numbers closely, there are some inconsistencies, but as I will show later they are not outside the expected measurement errors for this type of experiment.

For the hot water sparge he reports 98% conversion and 89% lauter efficiency.
0.98 * 0.89 = 87.2% mash efficiency. But, he reports a 89% to kettle efficiency, apparently 2% too high.

For the cold water sparge he reports 99% conversion and 88% lauter efficiency.
0.99 * 0.88 = 87.1% mash efficiency. But, he reports a 86% to kettle efficiency, apparently 1% too low. In this case he also reports a post boil efficiency of 88%, but it is not possible for the boil to improve efficiency (pre and post boil efficiencies must be the same unless you spill some wort.)​

Based on the above, I conclude that the two cells are the same w.r.t. efficiency, within the probable measurement accuracy of the experiment.

Let's look at the sensitivity of efficiency calculations to small errors in volume measurement.

If I start with 10 lbs of grain having a potential of 37 points/lb (370 total points), and collect 6.5 gal of 1.050 wort (6.5 * 50 = 325 points), I have an apparent mash efficiency of 325/370 = 0.8784 = 87.84%.

Now, if my wort measurement accuracy is +/- 0.125 gal, then I could measure either 6.375 gal (6.375 * 50 = 318.75 points) for an apparent mash efficiency of 318.75/370 = 86.15%. Or, I could measure 6.625 gal (6.625 * 50 = 331.25 points) for an apparent mash efficiency of 331.25/370 = 89.53%. That gives me a measurement range of over 3% for a 1 cup volume measurement error out of 6.5 gal. I don't think most brewers can measure volumes that closely. Therefore, I find no unexpected inconsistencies in Kai's numbers.

Now, think about the fact that there are also errors in gravity measurements, grain weight measurements, and grain potential numbers. It's going to be tough measuring efficiency to better than +/- 2% for a homebrewer.

Brew on