Conversion Efficiency

Brewing Processes
1

So, losing my mind a little bit…

I’m having a hard time getting consistent efficiency and I think it is in my conversion. I’ve been making a lot of adjustments to my process in an attempt to get above the 54% efficiency mark where I have been sitting. I’ve calibrated about 30 thermometers, 3 hydrometers, re-evaluated my grain crush, checked mash pH… I’ve really been trying to nail this down, and I seem to be getting no where.

This past weekend I brewed what was supposed to be a 5.5 gallon batch. I used beercalculus.com to build my recipe, I left the efficiency setting at 75, thinking that all the small changes I had made would add up. According to BC, my OG with a 75% efficiency should have been 1.079. (12lbs 2-row, 2.5 lbs specialties) I mash in an igloo cooler with a 1.5 qt/lb water:grain ratio. This time, that ratio was even a bit higher because I wasted a lot of heat really thoroughly stirring my mash around to wet all of the grains, so I had to add a little more than a galolon of boiling to the mash, so my ratio was closer to  1.94. The pH of my mash was 6.0 according to my pHydrion strips. A little high, but I didn’t have any citric acid lying around, so I went with it. I mashed for 60 minutes, stirring about 4 times over the hour. Temperature was still good when I started my lauter.

Now, the real problems. I collected my first runnings, and let them cool while I was lautering. At 90°F, the gravity was 1.050. In my mind, my first runnings should have been over 1.080. Feel free to tell me I’m wrong here. I was trying to collect 6.5 gallons, and then boil for an hour. I fly sparged with 170°F water until the runnings were plainly not sweet, but at this point I had collected 8.5 gallons. Even after overlautering, my total gravity in the 8.5 gallons was only 1.035. In my mind, 35 points in 8.5 gallons only equals 54 points in 5.5 gallons. (Again, feel free to tell me I’m wrong about this math) So, 1.054 is a far cry from 1.079. So I changed everything up and tried to add in some extra points with some DME. Added half a pound to the boil (all I had on hand thankfully), and then boiled for an hour before I started my hop addition. After being pretty fed up with what should have been a perfectly good brew day, I accidentally boiled for too long, and so I ended up with only 4 gallons of chilled wort, but it was at 1.084. Had I hit my target volume, and not added the DME (only 3.3 points in 5.5 gallons me thinks) I would have been at 1.058. Damn close to my first runnings, and WAY under my target.

So, now that you have read my overly long brew day story, what other information can I give you so you can tell me what the hell I’m doing wrong. I got lucky on this one that I will recover a beer close to what I wanted in the first place, but it sure would be nice to have the extra 1.5 gallons of beer when I work this hard for it. Also, I’d love to be able to brew a beer twice and get the same beer out. So far, reproduciblility is a long ways off.

Thanks so much in advance.

2
  1. Did you stir your runnings? If not that can give you a low reading. 2. Why did you keep collecting when you should of ended with around 7 to7.5 gallons that extra water will lower your starting gravity and does nothing for you.
3

You may be channeling. What type of manifold/mashtun setup do you have?

4

For one thing, I think the OG estimate was off.  I get 1.066 in Promash using your grist.

5

I did stir the runnings, I wanted to make sure and get an accurate value.

The runnings were still sweet, and nervous that I was looking at another 50% efficiency, I wanted to get all the sugars I could. Once I was over the 6.5 mark, I knew it would be a long boil to concentrate it. I figured, may as well boil a little longer. (Although I probably paid for the sugar with propane)

I have a 10 gallon igloo beverage cooler with a false bottom screen. Would channeling affect my first runnings? My understanding was that channeling would produce issues with the sparging/lautering.

6

How much are you lautering before you start the sparge? For instance are you draining the entire amount first or just establishing the flow rate to set the grain-bed and then starting the sparge?

7

Hmm, I was wondering if 12 lbs wasn’t light for this target. What efficiency considerations does promash make? Using data from Palmer’s book and a 75% efficiency I calculate 12lbs*27ppg/5.5g=1.059. All of a sudden, I am starting to think that beercalculus includes specialty grains in their calculations for OG…  Anyone else experienced this? Maybe this is my only issue, not doing the math the long way.

8

I drain until the mash level is just above the grain, then start siphoning in sparge water at a rate as close to equal as I can get it. I definitely started my sparge at a rate quicker than I wanted (built up about 1-2 gallons on top of my grain bed) but I don’t think that should have add a dramatic impact?

9

I entered 12 lb. of 2 row pale at 36 ppg and 2.5 lb. of C60 at 34 ppg to simulate your grist.  At 75% I get 1.071 for your OG.  I made a mistake earlier and had PM set for 5.5 gal., not 5.

10

Try batch sparging next time.  That will show you if your lauter system is the culprit.  Have you checked your conversion efficiency via Kai’s website?

http://braukaiser.com/wiki/index.php?title=Troubleshooting_Brewhouse_Efficiency#Determining_Conversion_Efficiency

11

My understanding is that fly-sparging can be enormously tricky to dial in. I batch-sparge and get excellent results.

12

Not to mention it is super fast. Quick sparge for sure. I got ~83% efficiency this last weekend on a Munich Dunkel. Works for me :slight_smile:

13

I was trying to collect 5.5 gal, but I think I don’t think beercalculus is very good at factoring that in.

This is actually the first time I have tried fly sparging, I usually batch sparge with the same results. I was trying the continuous sparge to see if investing in a proper fly sparging set-up might help.

According to Kai’s formulas, I had a conversion efficiency of 99%, but I’m not sure I understand how that could be possible. Does his table assume qts of water per pound of base malt? or the entire grain bill?

14

These were my understandings as well, which is why I used to batch sparge, but I’ve never seen anything that looked like 83%. When you say quick, how quick. When I batch sparged, I drained my tun, added sparge water, stirred it up, then let it sit for about 30 minutes before draining again. Was I wasting my time with the “sparge rest”? I’ll brew another bacth this weekend and go back to batch sparging.

15

I let it sit for about 10 minutes to settle down after adding the second sparge and stirring. Seems to set better that way but others don’t wait so long I think. Probably doesn’t make a difference. ::slight_smile: Waste of time is really subjective so I hate to speculate on that. I cut corners where I believe it is appropriate.

16

If you’re shooting for 5.5 gal. in the fermenter, then 1.066 is the estimate from PM.

17

Ignore the sparge, for now, you could screw around a lot with how fast you add or drain, what volumes you use, what type of manifold you have, or how long you let the sparge water sit, and you might see a few points improvement, but you would be chasing the wrong problem.  What you have is partially a math problem, but primarily a conversion problem.

First off, if you mashed 14.5# of grain with ~7 gallons, you might expect a  first running gravity of 1.065 with 100% conversion, not “over 1.080”.  Assuming that you had good mixing during your vorlauf, at 1.050 you probably had about 75% conversion.

Secondly, this was probably never going to be more than 5.5 gallons of a 1.067 beer, if everything had gone well and you got 100% conversion and the ~80% overall mash efficiency expected for a beer of this size.

Finally, with your 75% conversion and a quart of dead space, you would expect 1.036 at 8.5 gallons in the kettle.  You got 1.035, so you probably had 95-100% lauter efficiency.

Instead of following a list of random suggestions, some of which would be used to fix problems you don’t have, analyze your system like this and you can identify where your problem lies.  If you don’t measure basic elements of your process properly, like conversion and lauter efficiency, you’ll waste a lot of time making random changes instead of informed decisions.

In your case, focus on things that will improve conversion.  Crush is most important, then comes pH and mash schedule.  Optimized crush, could easily gain you 10%+ conversion.

I’ve never used those pH strips, so I can’t say if they are accurate or not.  If your pH is really 6.0, though, you need to get it down, because that is high enough to have an effect on your efficiency.  Probably closer to a 5% hit than the 25% that you are seeing, though.

I’d try an alpha amylase rest, too.  Mash at your usual temperature, say 152F, for a half hour or so, then infuse enough hot water to bring the temperature up around 158-162F and thin your mash out to ~1.7 qt/#.  Some brewers can gain 10%+ conversion efficiency with this change.

You need to include the entire grain bill for Kai’s table to work.  Specialty malts contribute nearly as much to gravity as base malts, and Kai’s chart is assuming a recipe with a somewhat average mix of grains.

18

Wow, Great Response, thank you!! This is the kind of post I was hoping for when I first asked the question. I’ll get some pH strips with better accuracy and measure again, hopefully that could be my issue, but I kind of doubt it. Most of my brewing buddies never even bother to measure their pH, use the same water, and relatively similar grain bills. They never seem to have an issue. (Then again, I also don’t think they typically measure efficiency…)

So with two rests like this, should I aim for 1.7qt/# at my strike, or for the final mash ratio (after the addition to bring the temp yup for the second rest)?[quote]
You need to include the entire grain bill for Kai’s table to work.  Specialty malts contribute nearly as much to gravity as base malts, and Kai’s chart is assuming a recipe with a somewhat average mix of grains.
[/quote]

I was assuming the entire grain bill, but I was making a math error. This calculation needs to be in points instead of SG. (SG-1).  So in reality, I had about an 84% conversion efficiency, which as you pointed out definitely suggests my conversion, and not my lauter.

Again, thank you so much. Is there a way to measure the crush that I am getting from my LHBS? The grain looks very well crushed,with lots of dust and no intact hulls, but perhaps I need to get more analytical here. I asked them what their mill was set to, but they didn’t know. Is that something I could measure for/with them?

19

I was assuming the entire grain bill, but I was making a math error. This calculation needs to be in points instead of SG. (SG-1).  So in reality, I had about an 84% conversion efficiency, which as you pointed out definitely suggests my conversion, and not my lauter.

Again, thank you so much. Is there a way to measure the crush that I am getting from my LHBS?

[/quote]
pH is generally not that much of an issue for conversion, though it can be and I’ve known brewers from areas with poor water whose conversion was impacted.  I’d move it down the list, but you might want to reign it in to prevent astringency in your beer.  Do you know if you are in an area with high bicarbonate?

For the alpha amylase rest, I aim for 1.7 qt/# or higher after the temperature step.  (I actually shoot for ~ 2 qt/# but it depends on the grist mass.)  The reason I recommended this is that I believe that it can make up for a less than optimal crush.  It’s tough when you are getting your malt crushed by a homebrew shop.

You could measure their gap, and I’m sure you could find plenty of threads with a long list of gap sizes that brewers prefer, but I have always optimized crush by gradually closing the gap until I got near complete conversion.  Ultimately, I believe that any serious homebrewer needs to break down and get a mill so that they have control over this aspect, but it took me 20 years to do that, so I can sympathize with brewers who don’t.

One easy thing to try at a homebrew shop is to ask for them to crush the grain twice.  That’s probably not going to be optimal, but it usually makes the largest chunks a bit smaller and can improve conversion in a case like yours.  What is common is that the larger grain chunks are not gelatinizing well.  Since we usually mash just below the optimal gelatinization temperature, making the grain smaller, thinning the mash, and raising the temperature can all tend to accomplish the same thing: making the starch available to amylase.

I think you might still be a little generous in your interpretation of Kai’s equations, unless I’m screwing up the math or misunderstand your volumes and gravities.  I’ve tried using them a couple ways and the highest conversion I have calculated for you was about 77%.

20

Hmm ok. Maybe you can walk me through this table then… I was figuring 14.5 lbs of grain, 7 gal (28 qts) of water gives ~1.94 qt/#, so I should have had a FW of ~1.065. I got 54 points, so (54/65) *100%= 83%. Where did I screw this up?