Optimum mill gap spacing for conditioned malt and recirculation mashing

I recently tried conditioning my malt with 2% by weight water before crushing at 0.030" mill gap. I got around 93% conversion efficiency. I am wondering what the expert malt conditioners out there are using for your mill gap spacing (with a 2-roller mill) and a recirculation system to get the best conversion efficiency and maintaining good recirculation speed?

When I condition my malt (2%) I use a mill gap of 0.028 - 0.030" on my JSP. I don't recirculate though.

I also condition at 2% and mill at .030 with a pretty consistent 80% Brew house efficiency. No recirculation, I just stir a lot.

SpeedYellow said:

When I condition my malt (2%) I use a mill gap of 0.028 - 0.030" on my JSP. I don't recirculate though.

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Do you also get around 80% efficiency into the kettle?

stickyfinger said:

Do you also get around 80% efficiency into the kettle?

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I don't know. I don't worry about conversion efficiency because I don't base my mill gap on efficiency, but rather what looks right to my eyes. I would probably be satisfied with .024-.026" gap, but I'm not going to mill it into flour just to hit some efficiency target.

My brewhouse efficiency is all over the board; 66% to 75%.

I'm planning to mill it as coarse as I can (after conditioning the malt) and still maintain good recirculation. I only really care about getting maximum conversion with good recirculation. I think I'll just keep crushing it a little tighter each time and see how much my conversion goes up. I'm guessing I'm pretty close. 0.020" to 0.030" seems like it is a good range according to what I have read.

I have a Kal clone and follow his steps. I have my mill at .045" and have 90+ efficiency

Edit:

I just realized this thread is about conditioning malt before milling. This is something I do not do.

BDB, I don't have a kal clone, instead using a norcal false bottom and/or SS braid with Concord pots. How long do you mash? I tried doing 0.045" and was only able to get around 80% conversion efficiency.

stickyfinger said:

BDB, I don't have a kal clone, instead using a norcal false bottom and/or SS braid with Concord pots. How long do you mash? I tried doing 0.045" and was only able to get around 80% conversion efficiency.

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I mash between 60-90min. Ramp up to 168 then sparge for 60-90min

Well, if you're really getting 90+% efficiency then you must be getting at least 95% conversion efficiency, as your lautering efficiency is not likely much over 95%. Maybe I'll one day try doing a coarser crush again, though the conditioning makes it unlikely I will want to try that again.

I do .045 with my RIMs setup and get around 80% brewhouse efficiency according to Beersmith.

I gap at 0.035" and condition the malt before milling. I brew with a RIMS and find that my efficiency hovers between 82 and 90 %.

0.030" seems pretty tight to me, but it could work since the husks are so intact. I'll stick with 0.035" for now.

I agree that 0.030" seemed kind of scary, but it seemed to recirc pretty well. The husks are so huge when conditioning the malt. I got around 93% conversion efficiency and my "to the kettle" efficiency was around 81.5%, though I shut off the sparge when the gravity reached around 1.012. I used to get around 90% to maybe highest of 93% conversion efficiency with a 0.039" dry crush, and the mash would get kind of slow sometimes on the recirc. I'm not gaining a huge conversion efficiency obviously. Even if I can just hover around 93% conversion efficiency with this awesome lautering with the conditioning, i will be happy.

mabrungard said:

I gap at 0.035" and condition the malt before milling. I brew with a RIMS and find that my efficiency hovers between 82 and 90 %.

0.030" seems pretty tight to me, but it could work since the husks are so intact. I'll stick with 0.035" for now.

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Do you measure conversion efficiency?

I tried 0.025" with conditioning this weekend and got 94.4% conversion, but my mash was not recirculating well for the first 30 minutes using a hose braid. You know, I'm always changing malts and varying temperatures, times and pH slightly, so it's hard to know if my conversion efficiency is basically the same or is going up a little. I want to crush as coarse as I can and still get good conversion consistently.

I think I need to go back to using my NorCal false bottom and go back to 0.03" and see if my flow is good right from the get-go with 90+% conversion. The false bottom is nice but the dead space is 2ish gallons, so it kills my lauter efficiency some when I use it. It should flow a lot better than my hose braid though. I think I just need a lot more batches using a consistent setup to see what crush I need.

I've seen people reporting close to 100% conversion, but I just can't seem to get there. I think my ppg assumptions are pretty close.

I just changed up my routine, so I only have one data point for you. I condition my malt like you though, and have a rims so I recirculate. I milled at .042 for this one. My conversion efficiency was 96%. I mashed for 60 minutes at 152 then ramped it up to 168 over 15 minutes and held it for 10 more.

brewmeister13 said:

I just changed up my routine, so I only have one data point for you. I condition my malt like you though, and have a rims so I recirculate. I milled at .042 for this one. My conversion efficiency was 96%. I mashed for 60 minutes at 152 then ramped it up to 168 over 15 minutes and held it for 10 more.

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Dude, no way! Hard to believe. Can you give me some exact numbers on what you did, what malt, how many pounds, etc.?

I don't see how that's possible, especially without sparging all the tannins out of your grains.

-BD

We're discussing conversion efficiency not lauter efficiency or what people call "mash efficiency". Look at Braukaiser's website for info

stickyfinger said:

Dude, no way! Hard to believe. Can you give me some exact numbers on what you did, what malt, how many pounds, etc.?

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Sure. Here are the specs:

10.5# Great Western 2 Row
1# Great Western White Wheat
1# Best Maltz Munich
.5# Best Maltz Dark Munich

Total Grain= 13# (This number is very exact, I measure out my grain with my wife's baking scales)

5.3 gallons or 21.2 qts of water added to the mash total (this of course could be off by a bit, brewing on this scale is such a ***** when it comes to percentage of error due to small batch sizes)

Mash Thickness= 1.63 qts/lb

According to Kai's chart this would result in a reading of 18.4ºP
My reading=17.7ºP (1.073 actually, but taken with a lab grade hydrometer at 67ºF, so very accurate, and converted)

17.7/18.4=.9619 or 96.19%

I use a 10 gallon Blichmann pot as a MT with their button louver false bottom and recirculate it through my rims tube and back into the pot via an autosparge.

There are the analytical, now for the antidotal. I used to crush my grain down to .035. I'd experimented a lot and even gone as tight as .025. I'm 49 batches in and I never really saw consistent gains (sometimes even lower mash efficiencies) from such a tight crush and I was having recirc issues and lower than desired lautering performance. So I went back to my .035" without thinking about it. I then listened to the seminar from from NHC last year on "How good is your grist" (here is a link if you are an AHA member:http://www.homebrewersassociation.org/how-to-brew/resources/conference-seminars/ it's under 2014). At this point I still kept on going at .035. Then I came across this article https://www.brewmagic.com/blog/follow-me-to-higher-efficiencies/. I decided to loosen up the mill to .042 (a little tighter than he suggest and the NHC seminar, but I'm a Hitchhikers Guide fan and it felt right). Seems to work great. My recirc and run off were better than ever. I attribute it to more even flow through the grain bed. Good luck man.

Yes, I agree. I plugged it into my spreadsheet assuming 37,37,35,35 for the ppg of the 2-row, wheat malt (?), munich and dark munich respectively and I get 96.4% conversion efficiency, great! I assume you checked your mill gap with feeler gauges? Your husks must look almost completely intact! I've also found that I get a pretty significant boost in conversion when I boost up for the mashout. Maybe I'll try conditioning with a mill gap of 0.042" on my next beer and see what happens.

I tried a 0.045" gap without conditioning maybe 10 brews ago, and I got a horrible conversion efficiency of 80%!!

Thanks for the input.

No problem. Yeah, I use feeler gauges to set the gap. If you do go with .042, I hope it works for you. I also hope it continues to work for me

I'm going with a tightish 0.035" tomorrow for a big Janet's Brown Ale clone batch with conditioning. I hope I don't get bad mash conversion. I'm sure the crush will be very fluffy.

Had some very nice, fluffy malt after conditioning. I used my FB with a hose braid under it to catch stray particles. It clogged up somewhat and flow was slow. Then, I blew off the hose braid by back-pumping and flow was fine. I guess I should ditch the hose braid.

I decided to do another beer after that one and used the same crush and conditioning with no hose braid. I had beautiful flow. My conversion efficiency on both batches was around 90%, not fantastic but acceptable.

The second batch had some pretty cloudy wort. I don't know if it was the Pils malt, the CaCl2 I had to add to get into pH range or what.

I think I'll stick with the 0.035" gap with conditioning and just a false bottom and see how my conversion efficiency stabilizes and how my flow is.