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Efficiency Issues

So, I did my second AG brew on Sunday, and only got 62% efficiency (determined by hand and via a couple calculators) and I’d really like to bring that up. I’m sure there are countless threads on this issue, including one of my own, but each situation seems unique, and the corrective measures I took after my first AG seemed to make things worse (I calculated 68% the first time, although I wasn’t nearly as careful with measurements, etc., during that session as I was during this one), so I thought I’d start a new thread.

Grain Bill:

  • -12 lbs 6 row[/*]
  • -.75 lb Crystal 60[/*]
  • -Potential Gravity @ 6.5 gallons: 1.069[/*]


  • -Double ground the grains at LHBS[/*]
  • -Batch sparged a la Denny's walk through[/*]
  • -Carefully measured strike and sparge water (5.5 gallons and 3.5 gallons, respectively)[/*]
  • -Mashed for 1 hour[/*]
  • -Dough in temp was 156*, dropped to 150* over the hour[/*]
  • -No pH adjustments (ColorpHast measured 5.0 at mash temps[b]***[/b], i.e., 5.3 after accounting for .3 offset)[/*]
  • -Drained almost exactly equal volumes (~3.25 gallons) from mash and sparge[/*]
  • -Lost ~1/4 gallon to gear (deadspace) during each draining.[/*]
  • -Vorlaufed first runnings, forgot to vorlauf the sparge water.[/*]

Pre-boil measurements:

  • -Volume: 6.5 gallons[/*]
  • -Actual Gravity: 1.043 (62%)[/*]


  • -Volume: ~5.2 gallons[/*]
  • -Gravity: 1.050[/*]

Note 1: All gravity readings were taken at 60*.

***Note 2: I’ve read in a couple of places that colorpHast measures pH the same at mash and room temps. One person suggested that Kai has noted this. Since reading that, another person has said this doesn’t make sense. If the latter is true, would the temperature offset account for an efficiency drop of 10%+? At any rate, I think next time I will test this for myself by cutting a strip in half, testing at mash temp, then place a sealed sample in the freezer to bring to room temp and check that, too.

Is there anything above, other than grinder setting at the LHBS, that would put me at 62% vs, say, 75%?

Could extremely soft water play a role (Ca: 15.7 ppm, Mg: 4.9 ppm), or is this a non-issue if pH is OK?

I am by no means a batch sparge expert - I typically fly sparge. But, I use about 1.25 quarts of water per pound of grain for my mash. It looks like you used 1.75 quarts per pounds. In my setup, that difference would be a large variable of the efficiency.

I am a batch sparger and there is nothing theoretically wrong with that ratio. The only downside would be if you used so much water for the mash that you didn’t sparge enough. I try ti adjust my ration so that what I get out of the mash runoff and the sparge runoff are about the same volume.

Calcium is a cofactor for one of the amylases (I don’t remember which offhand). Most brewing texts recommend around 30-50 ppm as the minimum in the mash. It could be that the grist would get you there anyway, but if the Ca and pH were both marginal it’s possible that 60 min wasn’t enough time for full conversion. Like I mentioned in the other thread, a first runnings gravity reading would be the way to verify that.

I checked my ColorpHast strips while brewing yesterday and they did show a variation in color based on the sample temperature. It was only ~0.1-0.2 though, so not quite as much as predicted. Of course, reading the strips is highly subjective anyway.

Something’s off with your volumes - with 13 lbs of grain, you should have left ~1.5 gallons of wort in the grain, so getting 3.25 gallons back from 5.5 gallons in the mash (and with a 0.25 gal dead space as confirmed by the sparge) means you’re either not draining long enough or your volume measurements aren’t accurate. But leaving 0.5 gallons of first runnings in the MT could account for a part of your lower efficiency.

Thanks for checking that. I’m assuming it was 0.1 - 0.2 lower at mash temps, which means I was actually at 5.1 - 5.2, not 5.3. Would this make an appreciable difference in extraction rates? I’m inclined to avoid adding calcium, as my water isn’t very alkaline, and I feel like I’d end up on a wild goose chase. I might settle for 68% rather than do that…but we’ll see.

I’ll be sure to take one next time. To get first runnings gravity, is it best to drain, then measure, or could I stir, measure, then vorlauf and drain if gravity is what I would expect, or keep mashing if it’s low? Also, what kind of efficiency should one expect from first runnings?

I actually ignored mash ratio this time and instead shot for equal volumes out from mash and sparge. By contrast, last time I mashed 11 lbs of grain at closer to 1.33 quarts/lb, and sparge volume was much higher than mash volume, but my efficiency was still pretty low (68%). That said, maybe the 6% drop between the two can be explained by the mash ratio? Why might using more mash water lead to ‘under sparging’? Wouldn’t more mash water just mean it could carry more sugar out during first runnings?

Last time out I calculated that I lost about 1.5 gallons/10 lbs of grain, and figured I’d lose just under 2 with 12.75 lbs, so 5.5 would’ve put me at 3.25. Tonight, I will use my 1 quart measuring cup to fill the kettle to the same level as combined runnings and see if I was remotely in the neighborhood of where I thought I was. Hopefully my tap water can get reasonably close to 150.

Finally, I kinda want to buy a grain mill in case the LHBS crush setting is playing a role, but I’d prefer to try different crushes settings first to see if it actually makes an appreciable difference. Anyone have any luck getting an LHBS to adjust for them? :wink: Also, is there any reason an LHBS would have different mills set to produce different crushes?

Most likely the reason for the low efficiency is the relatively high initial mash temperature. If you lowered the initial mash temperature to ~152F and kept it there for at least 20-30 mins, then you should see your efficiency increase. You may need to insulate your cooler more, as a 6F drop in temp over an hour is a little much. You may also see an increase in efficiency when you buy your own grain mill and crush at a lower gap width than your LHBS. Enjoy.

I check gravity after recirculating but before starting the runoff. That way if conversion isn’t complete I can extend the mash.

As far as conversion efficiency, I don’t know of any reason to target anything less than 100%. … Efficiency

Dadslackey was talking about fly sparging, in which case increasing the sparge volume will always increase efficiency. When batch sparging, efficiency is maximized when the runoff volumes are equal.

They might have different mills (or adjust the mill gap) for different grains. It’s pretty common for brewers to use a finer crush on wheat, for example.

OK, I just called my LHBS and asked about the gap on their grain mills (like, duh, why didn’t I do this 3 weeks ago?! :wink: ). They’re both set to .045", which is at the high end of ranges I’ve read (.035 - .050). Does this strike anyone as being too wide and possibly contributing to low efficiency? If so, and I get a grain mill, how low can I go before I start flirting with a stuck sparge?

[quote=“a10t2”]I check gravity after recirculating but before starting the runoff. That way if conversion isn’t complete I can extend the mash.

As far as conversion efficiency, I don’t know of any reason to target anything less than 100%. … Efficiency[/quote]
Cool, thanks.

I think that’s wide enough that it would have an effect. The default gap on most mills is 35-40 mil. It makes sense for a LHBS to do that, though. Their main concern is that a customer might have a stuck sparge.

Did you ask them if they would mill your grains twice?

They have self-serve mills. I ran all my grains twice this last time (62%), but not the first time (68%).

For some reason, I feel like 68% represents a soft ceiling based on mill gap, and 62% represents the same ceiling plus procedural and/or measurement errors on my part.

So, earlier tonight I filled up the kettle with my 1 quart measuring cup and weighed it at certain points (5 gallons, 6 gallons, and Sunday’s pre-boil wort level). Kettle marks and measuring cup are pretty closely tuned (hit 2 gallon mark at 8 quarts, 4 gallon mark at 16 quarts, etc.), and volumes derived via weight / 8.34 tracked with marked volumes pretty closely. Not sure what the latter is worth as the scale isn’t all that great. Anyway, I filled it up to where the wort was just before I started the boil, and determined via weight that it was about 6.5 gallons. Test water was at ~115*. I think that’s probably accurate to within 1/10 of a gallon, maybe 2/10, and puts me at ~63% efficiency.

Did you forget to stir as well? That can cause a significant hit.
As can leaving a large volume behind in the tun, which seems possible here.

What it comes down to, though is that efficiency below 75% almost certainly indicates a problem with conversion. While calcium does act as a cofactor and helps to stabilize amylase at high temperatures, I’ve mashed with calcium as low at 10 ppm and seen near 100% conversion, so I don’t believe that it is a major factor on my system. Perhaps it is more significant if you are mashing in hot and loosing a lot of heat during the mash.

I’d look at limiting dead volume with a dip tube, improving crush (you can always get some rice hulls to throw in if you ever get a stuck sparge), mashing thin and trying a step up to ~160°F for 10-20 minutes to improve starch gelatinization and finish off conversion.

Don’t worry about 100% conversion, the higher the conversion the less you need to lauter to get decent efficiency. At 100% conversion you can hit 70-75% efficiency without sparging, which is an interesting option whenever you make a beer in which you might want to limit extraction of husk flavors.

No, I stirred. I didn’t stir for a super long time, but I did make sure to get into all the corners and that there were no areas where the grain bed remained compacted/settled.

I will be sure to measure first runnings next time and see what kind of conversion I’m getting. Am I understanding correctly that mash gravity that is 100% potential for the volume means I got 100% conversion? Or, can it be over/under depending on that volume?

Sorry for the novel that follows, I’m coming in late here.

Here’s an example thread where Kai mentioned the colorpHast strips reading the same at mash and room temp. A while ago EMD had a .pdf on their website describing this phenomenon but it has been removed. viewtopic.php?f=5&t=89444&p=824593 IIRC from the .pdf, the shift was something like +0.2 units, and you’d expect a downward shift of -0.3 or so from the mash, so there could be a net -0.1 reading on the strip, if it had sufficient resolution. Given the inherent problems with interpreting a strip and comparing to a colored scale, it’s tough to split hairs over this. There’s nothing wrong with always taking the reading at room temp, then you don’t need to worry about it.

You will of course get different readings under different types of light, so make sure you are using tungsten light (aka incandescent) or sunlight. I also dab the strips with a towel before reading because the beer color can change the apparent reading, which is worse with darker beers.

All that said, I’m surprised your pH was that low with your grist. An all 6-row grist will yield a mash pH of ~5.8 in distilled water, and the little bit of crystal malt will shift it down maybe 0.2 or 0.3. You were probably sitting in the 5.3-5.6 range, which is just fine.

+1 to what shade said, you are leaving behind more wort than expected on the 1st runoff. Is there still visible standing wort when you decide to end the 1st runoff and start the sparge? If you rake down the grain a little bit, it should look relatively dry all the way through. Could be a loss of syphon if your pickup is too high off the bottom, or a stuck runoff. Have you tried running off plain water to see what the deadspace is without any grain?

Lower initial mash temp would make a more fermentable wort, but it will not increase mash efficiency.

Agreed with a10t2, that mill gap is very wide. Even milling twice, a lot of uncrushed or barely crushed kernels can fit through that gap. This is the main source of your problem, no doubt about it.

IME you can start having problems with stuck runoffs around .025" gap with an all-barely grist and the SS braid, but it can still be done if carefully vourlaufed. I started conditioning the malt before crushing and all my stuck runoffs went away, and kept the ~100% conversion efficiency. Denny, on the other hand, seems to crush just as fine (or finer) and never has runoff issues, so YMMV.

A good thing to look for to see if your stirred enough is dough balls. If the mash looks nice and uniform without any huge dough balls, you have stirred enough. I usually have a few small (quarter sized) dough balls after the inital stir that are gone at the end of the mash. I theorize that this accounts for the difference in efficiency when doing a mashout: dough balls are still present on dough in when the mash temp is high enough for complete barley starch gelatinization. By the time they dissolve, the temp is too low to fully gelatinize them and they are not converted. By mashing out (~160°-170°), the starch is gelatinized and quickly converted by the alpha amalyse that is now in overdrive due to the higher temps.

On the contrary, thanks for putting so much thought into it!

FWIW, my residual alkalinity is 19ppm, although my water’s softness makes 8 SRM (about where this brew is) the theoretical lowest I can go without acidifying. So, I was kinda surprised, too.

I have, and it’s about 1 quart. After first runnings, I tilted the cooler to get the water to flow towards the drain, moved the grains back, and confirmed that the water level was confined to deadspace. I did this after the sparge, too. About a 1/2 hour later, I noticed that the level had crept back up a bit, so I did one final running that produced very little.

It’s good to hear such certainty about this point :wink: . After reading about gap settings around the Web, .045" seemed quite high to me (most sites cite .050" as the high end cutoff). And, yeah, the grain didn’t really look any different after two crushes than it did after one. I put a grain mill on my b’day list, and my b’day is in a week, so hopefully this problem will go away soon.

Interesting. I was thinking I’d start with .035, but I’ve read it’s better to err on the low side and deal with a stuck sparge than err on the high side and get low efficiency. Given your comment and my experience to date, I think I’ll go with .030 or even .025 and see how it goes. Once I decide it’s brew day, I’m pretty much in it for the long haul anyway :wink: .

I haven’t ever checked for dough balls, but will be sure to next time. Interesting point regarding mashing out in order to convert starches that were bound up in dough balls early in the mash. I might reduce strike water by a gallon or a gallon and a half next time and get up to volume via a mash out infusion.

You may have already done it but check the calibration of your refractometer or hydrometer. It threw me for a loop my last brew, thought my efficiency had dropped to 65% which was perplexing since I had been running @ ~78% for quite awhile and I was brewing a smaller beer. Decided to check my my refractometer against my hydrometer (which I know is .03 off since I’ve checked it which RO water) and sure enough I needed to cal my refractometer, did that and they agreed within 1 point and my efficiency was actually 78%.

Wow. It’s crazy that it can swing so wildly based on calibration! I’m just using a hydrometer, and it’s off by about .02

I may get a refractometer and a pH meter someday, but I’d like to get my system in decent shape before chasing down the more incremental improvements that such tools would allow.

[quote=“ickyfoot”]I may get a refractometer and a pH meter someday, but I’d like to get my system in decent shape before chasing down the more incremental improvements that such tools would allow.[/quote]IMO, the $60 spent on a pH meter and a refractometer will be well worth it - being able to quickly read your gravity at any stage in the brewing process with just a drop or two of wort or beer is awesome and accurate pH readings are critical to AG. And both will make tracking down efficiency issues much easier.

Right on Shadetree. All I mean is, right now my primary concern is efficiency, and it’s really starting to seem like a mill is my best bet for attaining a significant improvement (hopefully 10% - 15% or more) on that front. Do you think improving my pH readings – or finer grain crush for that matter – might lead to that kind of uptick?

Undoubtedly, it would be nice if I didn’t have to cool wort samples, but given my problems with efficiency, extra soak time while I check first runnings gravity probably isn’t the worst thing.

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