Can't get mash efficiency above 65%

I've been gradually modifying my AG cooler mash tun system to try to get more accurate but my mash efficiency always seems to be stuck in the low to mid 60's. I'm not shooting for anything beyond 80% but 75% would be nice and I can't see why I can't achieve that based on what others have said.

Attached are pics of my mash lauter tun with one showing the collection cpvc piping turned on its side. The piping provides reasonable coverage I think and the slits are right against the base of the cooler. The cooler is a Coleman Premium 28Qt.
I have a second identical cooler which serves as the HLT.
I have a dial thermometer and a glass floating thermometer and I always use both for each stage (calibrating the dial from the floating at the start).
The only weird thing I've noticed with temps is that the floating tends to read lower than the dial in the mash. In hot water they read the same but put them into the mash and they seem to differ. Any ideas why? I let them set deep in the mash for a while but they never seem to agree and the glass floating thermom is always low (by as much as 10degF!).

For this last recipe (Austin Homebrew Imperial Agave Wit) the grain bill was 1 lb flaked oats, 4.75 lbs Belgian Pale Ale Malt, 3.75 lbs White Wheat.
I estimate (see comment on thermometers) my mash temp was 150-155 for just over an hour. I had about 14 quarts of mash water for the 9.5 lbs grain.
I then fly-sparged for over 1.5-2 hrs with water at about 170 degF. For the sparge I run the water from the HLT through a short piece of Silicon tube onto a plastic lid sitting on top of the mash, with the mash tun lid almost closed to keep the temp.
Normally I would run off 6.25 gallons but this time I wanted to gather all the sugars I could so I went over by a bit and then boiled down to 6.25G. I then measured the gravity using my spiffy new (calibrated) refractometer once the sample had been cooled down.
I calculated that the max yield for this grain bill @ 6.35G should have been around 1.055 but I measured 1.036 for an efficiency of >65%.

I'm really frustrated as I've tried to be as careful as possible when measuring temps and volumes. I'm pretty sure my mash-lauter tun design should be capable of better. I've sparged as slow as I can and I still seem to be stuck with a low efficiency. I've read some saying that grain crush can be a big factor. Has anyone else reported consistently low efficiencies from Austin Homebrew? I kind of doubt that's the problem to be honest but I'm stuck right now.

HELP!

Try a batch sparge, the flow pattern through your grain bed could be the path of least resistance right down near the inlet of you manifold and you are not effectively rinsing the grains.

If that doesn't help, look into the crush. Fly sparging as you have been doing lends itself to taller, narrower mash tuns that are prone to rinsing the grains as the sparge water travels through the grain bed...hope this helps?? Oh and i have found the inexpensive digital thermometers are pretty darn accurate....good luck and happy brewing.

+1 on checking your crush! I bought a BarleyCrusher and get in the high 70's. When I used to get my grain crushed by AHS it was usually 70-72%. I only batch sparge since the extra time to fly sparge hardly seems worth it.

I like to take a preboil reading so that I can separate the two processes. Pre and post boil. The biggest change I saw in efficiency was stirring the grain bed more.

Most likely you are having channeling issues. Here's a possible fix. Immediately prior to beginning the fly sparge, stir the grain bed thoroughly all the way to the bottom. Vourlaugh a gallon or two until the wort runs relatively clear and free of any particulates then begin lautering SLOWLY. Should this not significantly improve your lautering efficiency, then it probably is the crush. You should be able to hit 75% with ease.

Is your crush a constant? I've never dealt with AHB so is it crushed when you receive it or are you crushing it? Have you experienced the same numbers with grains that were run through different mills?

!!OFF TOPIC ALERT!!

I know this is not a solution to your issue, but 65% efficiency wort is probably the best QUALITY wort we can make; meaning a balance of least extraction of tannins and other flavor compounds that negatively affect the beer and wort sugar extraction. Of course, that is only true if your lautering techniques don't lead to channeling or over-sparging small percentages of the grist.

I'm usually getting 65%, tastes good so I just deal with it. I reckon I'd get more if I had a mill and if my grain was a little fresher, had been using some older grain recently. Them again, I've tried chasing efficiency before and it just lead to more trouble than it was worth lol.

wilserbrewer said:

Try a batch sparge, the flow pattern through your grain bed could be the path of least resistance right down near the inlet of you manifold and you are not effectively rinsing the grains.

If that doesn't help, look into the crush. Fly sparging as you have been doing lends itself to taller, narrower mash tuns that are prone to rinsing the grains as the sparge water travels through the grain bed...hope this helps?? Oh and i have found the inexpensive digital thermometers are pretty darn accurate....good luck and happy brewing.

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I agree with this. Your setup is not a good one for fly sparging- it's a great batch sparge set up, though! I bet with batch sparging you'd be over 70%, without any other changes.

Also, you NEED a good thermometer. You can get some decent ones for $20, but you need an accurate thermometer, no two ways about it.

Chasing efficiency is pointless, though. I mean, I get 72% with my system consistently, and that's the important thing. I'd be happy with a consistent 65%, as the "cost" would be about 1 more pound of grain as compared to a 75% recipe.

If you look at your recipes what is the difference in lbs of grain for 65% vs 75%? A pound or two? A high efficiency isn't quite as important as getting the same efficiency every time.

I believe your manifold design is fine for fly sparging.

Are you continuously adding sparge water all the way up until you stop collecting runoff or do you continue running off wort long after the sparge in-flow has stopped?

In any case, one way to check for channeling is to test the gravity of the runoff wort right about when you're done collecting runoff. Stop all liquid flow, stir the heck out of the mash again, then runoff about a quart and then grab a sample of the wort that comes out right after that. Compare the gravity of that new sample to the one you took at the end of your fly sparge runoff. If the second sample is a significantly higher gravity, your fly sparge is ineffective.

Phunhog said:

If you look at your recipes what is the difference in lbs of grain for 65% vs 75%? A pound or two? A high efficiency isn't quite as important as getting the same efficiency every time.

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It is important if the lower than expected brewhouse efficiency is from a low lauter efficiency - meaning that there is channeling and/or uneven draw of wort from the grain bed happening. That would lead to tannin extraction and other effects of extreme mash pH in the grains and husks around the channels.

Thanks for all the replies.
Re: channeling I thought that with my cooler shape being reasonably tall (12.5"L x 9"W x 9"D), my lautering pipes providing decent coverage and with a slow sparge that I wouldn't suffer much from channeling. I always do a good stir before sparging (although I haven't stopped to stir in the middle of a sparge. In general I re-circulate a 2-quart pitcher of wort (which I also use to time my sparge rate) and then set the HLT to match the mash-tun outflow (approx). I have enough space (7 gallons) in the HLT to do one continuous fly sparge until I've run off 6.25 G.

Re: Batch Sparging. I had avoided that since I had heard that in general it was less efficient. If I could get a consistent efficiency in the 70's with batch sparging then I'd definitely be up for that. Anything that shortens my brew time would be awesome since I have young kids and brewing on the weekends takes away from my playtime with them.

Re: Grain Crush. I have AHS crush the grain for me. One day I might by a mill but again I'm trying not to add more time (and expense and cleanup) to my brew day than is necessary. About how much time/expense/cleanup does a 10 lb grain crush involve?

Jonno.

Do you keep a good 2" of sparge water on top of the grain?

10 pounds of milling takes about 2 minutes. Clean up? Paint brush the rollers and hose out the bucket?

Batch sparging will take about a 1/4 of the time and be at LEAST as efficient.

@Bobby_M On the last batch I made sure there was at least an inch of water on top of the grain at all times and most of the time it was closer to 2". I was barely dripping the hot water in and on to a LME bucket lid to diffuse the flow. It's really exasperating.

Maybe I'll save up for the mill since it sounds fairly painless and quick and I can do it while the mash water heats up.

I'm definitely up for trying batch sparging to save the time now. Any suggestions on an article to read?

I believe AHS assumes around 70% eff with their crush so you're not too far off. I love AHS and used to order crushed grain from them all the time. My eff was always between 69-71%. Starting a little over a year ago with a finer crush, on my same system, same process, I upped my eff to around 86%. Shortly thereafter I started adding a little more calcium (calcium chloride and/or gypsum depending on the beer) to my mash (we have very soft water here) to drop the mash PH a touch. Ever since I've been parked in the 90-92% range.
BTW I batch sparge and I can't say that the greater eff has effected the quality of my beer one way or the other but it has allowed me to get higher gravity beers out of my system. I think the important thing is that your eff is consistent from batch to batch so you can formulate recipes accurately.

Suggestions for milling equipment?

jonnojohnson said:

I'm definitely up for trying batch sparging to save the time now. Any suggestions on an article to read?

Click to expand...

I believe Denny Conn has a good batch sparging article floating around that would be a good read.

WilliamWS said:

I believe Denny Conn has a good batch sparging article floating around that would be a good read.

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I think Bobby's info is good too.

I think Denny's website is dennybrew.com.

There is nothing wrong at all with batch sparging, and in fact I sometimes batch sparge even with my HERMS if I'm in a hurry! I get just as good efficiency with a batch sparge as a fly sparge.

You don't see recipes for beers with 90% numbers, you see 65% for BYO or maybe up to 75% for others. Relax on the 65% and work with some of the suggestions above. Don't chase the outliers.

Based on the OG numbers on the AHS recipe sheets I believe they use 75% mash efficiency. I'd like to get close to that so I don't have to worry about modifying recipes.

I like the idea of trying a batch sparge as mentioned. If that doesn't solve it, look again at the crush since your LHBS is doing it each time...they may just have a worn mill. That would explain it also.

No mention of how the water is being measured... how do you know that you actually used xx Quarts of water? Not to be facetious but this seems like a common cause for mystery efficiency issues.

Any chance you're using a bucket to measure those quantities? The math only works when everything is calibrated correctly. Bucket with markings are notoriously inaccurate.

Check your measuring devices - maybe using something accurate to measure water for mash/sparge but using a bucket to measure pre-boil wert volumes?
Just sayin'

.02c

- M

Bobby_M said:

I believe your manifold design is fine for fly sparging.

Are you continuously adding sparge water all the way up until you stop collecting runoff or do you continue running off wort long after the sparge in-flow has stopped?

In any case, one way to check for channeling is to test the gravity of the runoff wort right about when you're done collecting runoff. Stop all liquid flow, stir the heck out of the mash again, then runoff about a quart and then grab a sample of the wort that comes out right after that. Compare the gravity of that new sample to the one you took at the end of your fly sparge runoff. If the second sample is a significantly higher gravity, your fly sparge is ineffective.

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Very good advice.

Also, take the gravity of your first runnings. Make sure you're getting good conversion. Kai has a chart on his website (braukaiser.com) that shows what 100% conversion efficiency should be for various mash thicknesses. If you're getting less than ~85% conversion efficiency, you probably want to look at your crush and mash chemistry.

headfullahops said:

!!OFF TOPIC ALERT!!

I know this is not a solution to your issue, but 65% efficiency wort is probably the best QUALITY wort we can make; meaning a balance of least extraction of tannins and other flavor compounds that negatively affect the beer and wort sugar extraction. Of course, that is only true if your lautering techniques don't lead to channeling or over-sparging small percentages of the grist.

Click to expand...

Correct, knowing why you are getting 65% is useful.

@Rip, I've measured the diameter of my brew kettle a number of times and calculated the depth I need for 6.25G more than once. I always measure OG @ 6.25G and I think I'm pretty close.

@JKoravos and Bobby_M I do think that sounds like a good idea but honestly I can't afford to brew often enough to try every permutation of my process.

I'm thinking I will try a batch sparge next time to see how things go. I'll stick with the LHBS doing the milling for control (and b/c it will be a while before I'm willing to buy my own mill).

Since I'm now wondering whether I wasn't stirring the grain-bed often enough, when do people recommend doing this?
* How often during the mash?
* If at the end of the mash, how much time should I leave to let it settle before the re-circulation step? I guess the same applies to how much time to settle after adding the 2nd batch sparge water before re-circulating.

I like to stir things up really good at the beginning and end of the mash, and occasionally I'll stop and stir in the middle of my fly sparge (obviously I re-vorlauf before resuming the sparge). I don't allow any "settling time" after stirring. I stir like a madman and recirculate right away until the wort runs clear. My ice cube rig hits a consistent 86% eff, FWIW.

I wonder if your manifold design might have something to do with it. Great longitudinal coverage, but I wonder if the two "outer" drains are too close to the walls and are creating channels along the long walls of the cooler. I wonder if you wouldn't get better efficiency with the outer drains removed?

jonnojohnson said:

@JKoravos and Bobby_M I do think that sounds like a good idea but honestly I can't afford to brew often enough to try every permutation of my process.

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The two options we presented you can be done in one batch, without affecting the batch. Pretty simple stuff.

jonnojohnson said:

Since I'm now wondering whether I wasn't stirring the grain-bed often enough, when do people recommend doing this?
* How often during the mash?
* If at the end of the mash, how much time should I leave to let it settle before the re-circulation step? I guess the same applies to how much time to settle after adding the 2nd batch sparge water before re-circulating.

Click to expand...

When I mash in, I stir well. Then check the temperature throughout, and if it's different in one place than another, stir some more. I stir again, and check the temperature once last time. Then cover and walk away. I know I lose about 1 degree, so no need to check again, or to stir again.

For batch sparging, you just drain the wort. Add 1/2 the sparge water (you can do it in one batch you get slightly better efficiency with two separate additions) and stir well. Vorlauf and drain. Do it again. No waiting, no settling, just let 'er rip. I like to crack the ballvalve open slightly when starting to vorlauf, but then open it up all the way. It takes just a couple of minutes to drain.

JKoravos said:

The two options we presented you can be done in one batch, without affecting the batch. Pretty simple stuff.

Click to expand...

You're right they are simple, maybe it'd be more accurate to say that I'm impatient. It will be a few more weeks till I brew again and I guess I'm convinced now that I want to try a batch sparge rather than play around trying to figure out where the fly sparging was going wrong. If the batch sparge doesn't help much then I guess I'll either try your suggestions on a fly sparge or start saving up for a mill.

Just fyi (OT) on the gravity measurements, since I just got my new refractometer with automatic temperature correction, can I really just put drops of hot wort on it (from the runnings) and it will read accurately or do I still need to cool it some?

jonnojohnson said:

You're right they are simple, maybe it'd be more accurate to say that I'm impatient. It will be a few more weeks till I brew again and I guess I'm convinced now that I want to try a batch sparge rather than play around trying to figure out where the fly sparging was going wrong. If the batch sparge doesn't help much then I guess I'll either try your suggestions on a fly sparge or start saving up for a mill.

Just fyi (OT) on the gravity measurements, since I just got my new refractometer with automatic temperature correction, can I really just put drops of hot wort on it (from the runnings) and it will read accurately or do I still need to cool it some?

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You want to cool it some. HOWEVER, two drops cool really fast! The ATC isn't about the wort temperature, it's about the instrument temperature. The drops of wort cool to instrument temperature very quickly though. You can pull the sample, drop it on the refractometer and close it up and it'll be a good reading.

The only time I pull the sample and give it more than a couple of seconds is preboil, when I've actually got the runnings combined and just about at a boil. I found that it takes a few more seconds to get it at a good temperature.

I pull my sample with a medicine dropper, then blow on the dropper or a few seconds to get it kind of cool, then put it on the refractometer. That seems to work well. Even if I let the refrac sit for a while with the sample in it, the reading doesn't change.

It's your crush. I never got over 72% with AHS's crush, usually 65-70%. They leave it very, very coarse to prevent stuck sparges I guess.

My first batch with a barley crusher: 86%. I now get between 75-86% depending on how big the grain bill is.

I usually have a glass of icewater sitting there while I'm brewing anyway so I'll jiggle the bulb of the pippette in the water for 10 seconds, then drop it on the prism.