Mill Gap for BIAB (Efficiency Problems)

[Epos7]

A few weeks ago I brewed my first batch of beer. I used the Zombie Dust clone recipe on here. I used the mill at my LHBS, and did a triple crush. I got about 54% brewhouse efficiency.

The mill at the LHBS looks like it has seen better days, so I elected to purchase my own mill hoping I could improve my efficiency with a better crush. I bought the Monster Mills MM2-Pro SL (the one with helical slotted rollers). I milled my grains with my new mill and brewed my second batch of beer yesterday. I followed the same recipe because I wanted to keep all the variables the same and see if my efficiency improved. The only change I made was to add 0.75 gallons to my starting water volume as I didn't collect the full 5 gallons on my first attempt.

The second time around I did collect a full 5 gallons, but my brewhouse efficiency remains at 54%.

The OG was lower on my second batch - 1.047 vs 1.053. I'm trying to hit 1.062 as called for in the recipe. The weird thing is that my gravity at the end of mashing was higher for the second batch than the first - 1.033 vs 1.023.

I'm starting with RO water and adjusting with gypsum and CaCl to hit the balanced water profile on Brewers Friend. That amounts to 1g of CaCl for both batches, 5.5g gypsum for the second batch, 5g gypsum for the first batch. I'm adjusting pH with 2mL 88% lactic acid, and confirmed my pH during mash was 5.35.

I'm hitting my mash temps, and for the second batch I did a better job of keeping the kettle insulated. Starting mash temp was 153F, and it was still 151F 30 minutes into the mash. I'm stirring the wort for several minutes at mash in, and at 15 minute intervals throughout the mash.

I'm spending several minutes squeezing the bag after the mash is over. For my second batch, I lost 0.75 gallons to grain absorption/evaporation during the mash. With a 12lb grain bill, that amounts to 0.06 gallons per pound of grain.

Given all the steps I've described above, the only thing I can think of that would be contributing to such low efficiency is my grain crush. With the Monster Mill, it came set from the factory at a 0.045" gap. I'm using a pretty beefy low-RPM, high-torque Makita corded drill, and I couldn't get the rollers to turn at that setting. I backed it off to 0.050" and while the drill was working pretty hard, the crush that I got looked better, and a little finer, than the crush I got running my grains through the LHBS mill three times.

What is a typical mill gap for BIAB? I'd be happy if I could hit 70% efficiency, but that's a long way away. I suspect the mill gap for a helical roller is a bit different than a knurled roller, but at least I might be able to get a better idea of what I need to be doing. I don't think I can mill at a lower setting than 0.050" for the first crush, I may need to start there then adjust the mill to a lower setting and crush a second time. I would prefer not to have to mill twice, but it's the only thing I can think of that could be holding back my efficiency.

Here is a picture of the crush on my second batch. All grains were broken into multiple pieces, and there was a good deal of flour in the crush as well. I conditioned the grain prior to crushing.

https://dl.dropboxusercontent.com/u/16976040/2016-09-03 15.08.35.jpg

Any input appreciated, thanks!

 

[VT_jlee]

I use 0.03 on my Cereal Crusher and with one pass I usually get 75%-80% efficiency. Last few brews have been 78% spot on. I mill the grain by hand so I am not sure if a drill can handle it that low of a setting or not.

 

[RedlegEd]

Based on the photo of your grist, it looks pretty nice. I think your higher conversion SG of 1.033 v 1.023 shows you got an extra 10 points from your crush. A few questions for you:

Is your grain fresh, or at least been stored properly?

I use a Schmidling Malt Mill with a fixed factory setting of .045 and my crush on conditioned grain looks similar to yours and my conversion efficiencies are fairly high. Are you starting your mill hopper empty, and adding grain once it starts turning, or trying to start with the hopper full? Your drill might not have the power to get it started under a load, but might be able to muscle through once it has a running start.

What are you using to calculate your efficiencies? I'd recommend putting your recipe and numbers into Brewers Friend (it's free.) When you use the "Brew" function and input your numbers (i.e. starting volume, ending volume, mash SG, volume into the fermenter, OG into the fermenter, etc.) it will compute all of your efficiencies for you and give you a final brew house efficiency.

Based on what you've described, your process seems sound. The only other thing I can think of that would cause you to have such a low OG might be not boiling off enough wort to get the OG higher.

 

[wilserbrewer]

While hard to tell from the pic of your crush, I think you need to tighten your mill, quite a bit.

A mill with 2" rollers will require a lot of torque!!!!

Are you using a powerful 1/2" low speed drill?

If the 2" mill is very hard to turn at a tight gap, I would try taping some sheet metal or cardboard inside the hopper such that only 2 to 3" of the roller is milling grain, reducing the feed and making the rollers turn more easily at a tight crush. I recently purchased a Kegco 3 roller mill and was very surprised at how much torque is required to spin it at a tight gap.

My guess is that you over achieved with your mill purchase, and a "pro" mill may take "pro" means to turn it at a tight gap. .050 seems too wide to me, for BIAB lots use 0.30 - 0.35.

 

[wilserbrewer]

The second time around I did collect a full 5 gallons, but my brewhouse efficiency remains at 54%.

The OG was lower on my second batch - 1.047 vs 1.053. I'm trying to hit 1.062 as called for in the recipe. The weird thing is that my gravity at the end of mashing was higher for the second batch than the first - 1.033 vs 1.023

You should be collecting approx 6 gallons for a 5 gallon batch?

Your measurements appear mathematically impossible to me, unless you are boiling off half your wort? Reported mash gravity of 1.023 appears inaccurate, or impossible given your OG?

For someone to look at this closely, you will need to post the recipe, volumes and gravity obtained? Gravity measurements without accurate volume measurements are meaningless.

If I had to guess, I'm thinking more water and more crush...

 

[dmtaylor]

+1 to everything @wilserbrewer said.

I think the crush looks poor based on the picture. You need to crush finer by setting the mill gap tighter. That is all.

 

[Radboud]

Also be sure to break up any dough balls that might have formed. Stirring helps but I find I need to hunt the ones that sink to the bottom down and break them up with a mash paddle.

 

[Epos7]

Thanks all. Here are a few notes about my process:

- Grains are fresh, and stored in food grade HDPE buckets with Gamma Seal lids.
- I have been starting the rollers when the hopper is full, but I'll try getting them spinning before adding grain. That's a good thought.
- I'm using Brewer's Friend to calculate my efficiencies. 54% is my brewhouse efficiency on both batches so far.
- My first batch I only collected about 4.5 gallons. For my second batch I bumped my starting water volume from 7.34 to 8 gallons and collected about 5.25 gallons. I calculated 7.34 gallons for the first batch using the Priceless BIAB calculator.
- I didn't realize I should be collecting 6 gallons for a 5 gallon batch. My biggest carboy is 5.9 gallons so I guess I need to shoot for just under a 5 gallon batch size.
- Drill is a high torque, low RPM corded drill with a 1/2" chuck.
- The hopper came with two wings that when attached would decrease the width of the rollers that grain is being fed into from 6" to about 4". I didn't attach them because they weren't mentioned in the instructions and I thought they might be for use with smaller mills. I'll give them a shot, they might make turning the mill easier.
- Gravity measurements are taken with a Milwaukee digital refractometer which reads in brix. I then convert to gravity. Samples are collected with a thief into 50mL beakers, covered with foil, and allowed to cool to 23-24C before I take a brix reading.

- First batch: ~4.5 gallons collected, 1.053 OG
- Second batch: ~5.25 gallons collected, 1.047 OG

I think I have a few things to try. I'll add the wings to the hopper which will hopefully make the roller easier to turn and allow me to decrease the mill gap to around 0.030". I'm also in the process of etching volume markings into my two carboys. I did my 5 gallon carboy, and I'll do the same to my 6 gallon carboy when it's empty again. This should help me get a more accurate idea of how much wort I'm collecting.

 

[wilserbrewer]

- I didn't realize I should be collecting 6 gallons for a 5 gallon batch. My biggest carboy is 5.9 gallons so I guess I need to shoot for just under a 5 gallon batch size.

A 5.9 gallon fermenter is too small IMO if you hope to conveniently ferment a 5 gallon batch (5 gallons finished volume). Likely you will need to a
start with 5.5 gal to the fermenter, but then you will likely need a blow off tube which will blow more volume out the top. IMO try a 7-8 gallon bucket fermenter...

Thanks all. Here are a few notes about my process:



- The hopper came with two wings that when attached would decrease the width of the rollers that grain is being fed into from 6" to about 4". I didn't attach them because they weren't mentioned in the instructions, and I assumed they were intended for mills with 4" rollers, not 6". Maybe they are supposed to be used. I'll give them a shot, they might make turning the mill easier.

I believe the inserts supplied are intended to be installed with the 6" rollers. In addition to reducing the grain feed, they also function to keep grain and dust out of the roller ends, the roller ends can bind on the mill plates if they get packed with dust leading to a stubborn lazy slave roller.

Good luck getting it all sorted, shouldn't be to difficult....that's a helluva mill you have there

I think if you can get the mill to turn at 0.035 you will see a jump in efficiency, and I think this can easily be done with installing the inserts, and if you still can't turn it I would duct tape and cardboard the mill opening to 3". Milling should still be plenty fast with the reduced opening due to the nice large 2" rollers.

If this is the Makita you mention,
http://www.homedepot.com/p/Makita-8...17xAD466eq5HFrW1eGQ-8aAiVh8P8HAQ&gclsrc=aw.ds

It is 8.5 amp, 600 RPM but I do notice it is constant and not variable speed...I have a hunch that with the mill inserts installed the mill will turn much easier.

 

[Epos7]

A 5.9 gallon fermenter is too small IMO if you hope to conveniently ferment a 5 gallon batch (5 gallons finished volume). Likely you will need to a
start with 5.5 gal to the fermenter, but then you will likely need a blow off tube which will blow more volume out the top. IMO try a 7-8 gallon bucket fermenter...

How much head space should I be looking to leave in the fermenter? I might pick up one or two 6.5 gallon glass carboys - think that would be sufficient for a 5 gallon batch?

I believe the inserts supplied are intended to be installed with the 6" rollers. In addition to reducing the grain feed, they also function to keep grain and dust out of the roller ends, the roller ends can bind on the mill plates if they get packed with dust leading to a stubborn lazy slave roller.

Good luck getting it all sorted, shouldn't be to difficult....that's a helluva mill you have there

I think you're right. My logic was that installing them could lead to uneven wear, but wear probably isn't going to be an issue for me on this mill anyway.

 

[JONNYROTTEN]

A good and easy measure of a good gap is your basic gift card.I stick it between the rollers and tighten to the point I can slide it up and down with the rollers moving but without excess force on the card..get good efficiency.Others do the same

 

[wilserbrewer]

How much head space should I be looking to leave in the fermenter? I might pick up one or two 6.5 gallon glass carboys - think that would be sufficient for a 5 gallon batch?



I think you're right. My logic was that installing them could lead to uneven wear, but wear probably isn't going to be an issue for me on this mill anyway.

A 6.5 glass carboy should be big enough, but I just feel obligated to mention I find glass to be too dangerous to worth the merits. Buckets are cheaper, safer and much easier to clean IMO...but some love glass so follow your heart I guess

I wouldnt be concerned with mill wear, I believe Monster designed those plates for a reason and they should be installed. The did not supply them by accident AFAIK, they are pretty standard on most mills.

 

[Epos7]

A 6.5 glass carboy should be big enough, but I just feel obligated to mention I find glass to be too dangerous to worth the merits.

I buy covers for all my glass carboys from carboy.net - that way if the carboy does break, the glass is all contained within the cover. I also have handles mounted on the necks, and the covers provide several other handles to grip. It makes moving them around much more manageable. I'm not claiming this makes them 100% safe, but I do think it's substantially safer than using a bare, slippery, glass carboy that could send glass shards everywhere if it breaks.

 

[Epos7]

You should be collecting approx 6 gallons for a 5 gallon batch?

I'm a little confused by this, as my impression was that "batch size" referred to volume of wort into the fermenter, not volume of beer into the bottling bucket.

For example, on the Zombie Dust recipe I've been brewing, found here on the forum, the OP lists the recipe for 6 gallon batches, then in a follow-up post states:

I usually do 5.5-6g batches to account for trub and hop loss. Here is the above scaled down to 5g (and rounded off into even weights):

So it seems that there are two schools of thought - one that recipes specify volume into the fermenter, and another that recipes specify volume of drinkable beer.

Thanks for walking me through this stuff!

 

[wilserbrewer]

You are correct, perhaps I misspoke a bit.....JMO to go thru all the effort for 4 1/2 gallons drinkable seems disappointing. lol.

 

[Epos7]

You are correct, perhaps I misspoke a bit.....JMO to go thru all the effort for 4 1/2 gallons drinkable seems disappointing. lol.

Phew, thought I was going crazy. I agree, though, that more beer is better Just means I'll have to brew more frequently I guess.

 

[1MadScientist]

- Gravity measurements are taken with a Milwaukee digital refractometer which reads in brix. I then convert to gravity. Samples are collected with a thief into 50mL beakers, covered with foil, and allowed to cool to 23-24C before I take a brix reading.

- First batch: ~4.5 gallons collected, 1.053 OG
- Second batch: ~5.25 gallons collected, 1.047 OG

What was your brix reading(s)? What does 5.25 gallons collected mean, is that what went in the fermenter?

Do you have any brix readings at the beginning or ending of the boil along with those volumes? A 79% kettle efficiency should be possible.

Can you post a link to the recipe?

 

[Epos7]

What was your brix reading(s)? What does 5.25 gallons collected mean, is that what went in the fermenter?

Do you have any brix readings at the beginning or ending of the boil along with those volumes? A 79% kettle efficiency should be possible.

Can you post a link to the recipe?

Here's the recipe, I used the one in the second post for a 5 gallon batch:

https://www.homebrewtalk.com/showthread.php?t=303478

5.25 gallons into the fermenter.

For my second attempt, I started with 8 gallons of water.

Beginning of boil: 7.25 gallons, 8.3 brix
End of boil: 5.25 gallons, 12.0 brix
In fermenter: 11.7 brix

I think my brix reading in the fermenter is a little lower than at the end of boil because I had to wait for that sample to cool. I cover my samples with foil, but I'm guessing there's still a small amount of evaporation.

 

[Epos7]

I installed the two inserts in the hopper, and was able to dial down the mill gap and successfully crush at 0.035".

https://dl.dropboxusercontent.com/u/16976040/2016-09-07 19.17.35.jpg

 

[1MadScientist]

It's not hard to get 80% kettle efficiency on a 1.065 OG with a standard crush.. You came in at 60%. Something else is going on here. pH or something else.

 

[Epos7]

It's not hard to get 80% kettle efficiency on a 1.065 OG with a standard crush.. You came in at 60%. Something else is going on here. pH or something else.

pH was 5.35, right where it should be.

 

[Epos7]

I brewed again today. I chose a different recipe this time - Mosaic Honey Wheat, also found here on HBT:

https://www.homebrewtalk.com/showthread.php?t=470698

Grain bill calls for 4lbs 2-row, 4lbs wheat, 1lb honey malt.

For this brew I adjusted my mill gap to 0.035" using a set of feeler gauges. I verified the thickness of the feeler gauge using a set of digital calipers. I conditioned my grain the day before milling by misting it with RO water, mixing well, and repeating several times. Target OG was 1.052.

Here's my process:

-Fill kettle with 7.75 gallons RO water.
-Add 5.5g gypsum, 1g CaCl, 1.5mL 88% lactic acid.
-Heat strike water to 157F.
-Add bag, grains, stir for two minutes. At this point my mash temp was 152F, which is exactly what I was targeting.
-Insulate kettle with sleeping bag.
-At 45 minutes, my mash temp was 151F, refractometer sample 5.2 brix @ 22.8C, pH 5.46.
-At 30 minutes, my mash temp was 150F, refractometer sample 6.4 brix @ 23.1C, pH 5.51.
-At 15 minutes, my mash temp was 149F, refractometer sample 6.8 brix @ 23.3C, pH 5.53.
-At 0 minutes, my mash temp was 146F, refractometer sample 6.7 brix @ 23.7C, pH 5.52.
-Add 0.25oz FWH.
-Check pre-boil volume: 7.35 gallons.
-Bring to boil. At this point I checked the water temperature with my thermometer to make sure it was reading accurately. Thermometer read 211F at boil.
-Check brix @ 30 minutes: 8.4 brix @ 23.0C.
-Add 0.75oz hops @ 15 minutes.
-Place chiller in kettle.
-Add 1.0oz hops @ 0 minutes.
-Complete boil for 60 minutes.
-Steep for 10 minutes.
-Chill for ~10 minutes to ~85F.
-Check final volume: 5.5 gallons.

I also purchased a hydrometer for this brew, to rule out my refractometer as a source of error. At this point I collected a hydrometer sample. Hydrometer read 1.040. Refractometer read 9.4 brix @ 23.0C.

I ended up with 5.5 gallons in the kettle, and only room for 5 gallons in the fermenter, so I overshot a little bit.

I couldn't find German Honey Malt in Brewer's Friend, so I used Canadian Honey Malt. At 1.040 SG, assuming 5.5 gallons collected, that gives me 64% brewhouse efficiency. If I bump it down to the 5 gallons I actually collected, I'm at 58%. An improvement, but still pretty bad. I'm at a loss for what I could be doing wrong. I may just have to move forward assuming ~60% efficiency. I'm not nailing my starting water volume, and that's something I hope to be able to dial in, but it only explains a small part of my poor efficiency.

 

[doug293cz]

I brewed again today. I chose a different recipe this time - Mosaic Honey Wheat, also found here on HBT:

https://www.homebrewtalk.com/showthread.php?t=470698

Grain bill calls for 4lbs 2-row, 4lbs wheat, 1lb honey malt.

For this brew I adjusted my mill gap to 0.035" using a set of feeler gauges. I verified the thickness of the feeler gauge using a set of digital calipers. I conditioned my grain the day before milling by misting it with RO water, mixing well, and repeating several times. Target OG was 1.052.

Here's my process:

-Fill kettle with 7.75 gallons RO water.
-Add 5.5g gypsum, 1g CaCl, 1.5mL 88% lactic acid.
-Heat strike water to 157F.
-Add bag, grains, stir for two minutes. At this point my mash temp was 152F, which is exactly what I was targeting.
-Insulate kettle with sleeping bag.
-At 45 minutes, my mash temp was 151F, refractometer sample 5.2 brix @ 22.8C, pH 5.46.
-At 30 minutes, my mash temp was 150F, refractometer sample 6.4 brix @ 23.1C, pH 5.51.
-At 15 minutes, my mash temp was 149F, refractometer sample 6.8 brix @ 23.3C, pH 5.53.
-At 0 minutes, my mash temp was 146F, refractometer sample 6.7 brix @ 23.7C, pH 5.52.
-Add 0.25oz FWH.
-Check pre-boil volume: 7.35 gallons.
-Bring to boil. At this point I checked the water temperature with my thermometer to make sure it was reading accurately. Thermometer read 211F at boil.
-Check brix @ 30 minutes: 8.4 brix @ 23.0C.
-Add 0.75oz hops @ 15 minutes.
-Place chiller in kettle.
-Add 1.0oz hops @ 0 minutes.
-Complete boil for 60 minutes.
-Steep for 10 minutes.
-Chill for ~10 minutes to ~85F.
-Check final volume: 5.5 gallons.

I also purchased a hydrometer for this brew, to rule out my refractometer as a source of error. At this point I collected a hydrometer sample. Hydrometer read 1.040. Refractometer read 9.4 brix @ 23.0C.

I ended up with 5.5 gallons in the kettle, and only room for 5 gallons in the fermenter, so I overshot a little bit.

I couldn't find German Honey Malt in Brewer's Friend, so I used Canadian Honey Malt. At 1.040 brix, assuming 5.5 gallons collected, that gives me 64% brewhouse efficiency. If I bump it down to the 5 gallons I actually collected, I'm at 58%. An improvement, but still pretty bad. I'm at a loss for what I could be doing wrong. I may just have to move forward assuming ~60% efficiency. I'm not nailing my starting water volume, and that's something I hope to be able to dial in, but it only explains a small part of my poor efficiency.

Nine pounds of grain, mashed in 7.75 gal of water should give you a final mash gravity of 9.64 to 9.87 Brix (Plato.) So, for some reason your conversion efficiency looks to still be only about 67%. With a good crush and mash process, you should be able to achieve 95% conversion efficiency or better. From your process description, I can't see anything obvious that would lead to conversion efficiency as low as you are getting.

Brew on

 

[oujens]

For batch sparge, I set my mill to .033 and get 80% efficiency. I think you need to go tighter on your gap. From everything I've read, you should mill with a tighter gap for BIAB than you would a traditional set up assuming no recirculation. I read the description of crushed grain as "coarse corn meal". Your second picture seems to have some grains somewhat intact.

 

[dmtaylor]

I brewed again today. I chose a different recipe this time - Mosaic Honey Wheat, also found here on HBT:

https://www.homebrewtalk.com/showthread.php?t=470698

Grain bill calls for 4lbs 2-row, 4lbs wheat, 1lb honey malt.

Okay, so I spent about an hour analyzing all your data, because I'm a really geeky engineer like that. You provided really excellent notes, by the way -- this was immensely helpful in figuring out what's going on. My conclusions based on my experience and scientific analysis:

*With this recipe and volumes, even if you had sparged, you should have expected only about 80% brewhouse efficiency and OG 1.047 (12.2 Brix), not 88% and 1.052 (13.3 Brix). So, your initial expectations were a bit lofty and unreasonable, especially considering no sparge (you didn't sparge, right?). What tipped me off to this was only 9 lb malts in a 5.5-gallon batch ---- the norm for a 1.052 beer, gut feel, should be more like 11 lb or something in that neighborhood. Just 9 lb is not enough malt for that gravity, unless you crush really well, sparge a lot, boil longer, etc.

*Wheat kernels are smaller in size than barley kernels. As such, if you achieved a good crush of the barley malt at say 80% awesomeness as I would have expected per above, but only cracked the wheat kernels about 50% of the way (just an inadequate crush), this would give an OG 1.039, which is about exactly what you got. So I think the use of wheat is almost certainly partially to blame here. If you'd gone with 100% barley, this might not have happened or symptoms would not be as bad. Need to set the mill tighter if you're using wheat, or double-crush or something to help crack the wheat better.

*Your refractometer or hydrometer must be out of calibration. Test both in plain water at 22 C and see if they read 1.000. If not, well, there's that.

*Your pH meter might also be reading a bit high. With the RO water, salts and acid additions that you used, I would have expected a mash pH of about 5.3, so I'm surprised that it was 5.5. Could be less than awesome RO water quality with too much impurities? might be time to change the membranes? I don't know. Think on this a bit.

Hope this gives you some good answers and things to consider. Cheers. And don't thank me, I enjoy doing stuff like this, it's "fun".

 

[1MadScientist]

I'm not nailing my starting water volume, and that's something I hope to be able to dial in, but it only explains a small part of my poor efficiency.

You did nail the starting strike water in the brew I looked at before. I ran that recipe through the BIABacus, which I use. I mentioned kettle efficiency, because that's all we have to go on from you. If you are adding the entire contents of the kettle after the brew into the fermenter, which is okay, you could have as much as 3/4 gallon of trub in there. Brewhouse efficiency is not known until all the loses are accounted for.

If you are withholding the trub from the fermenter, then we are not getting the full picture of the loses, volumes.

 

[oujens]

Okay, so I spent about an hour analyzing all your data, because I'm a really geeky engineer like that. You provided really excellent notes, by the way -- this was immensely helpful in figuring out what's going on. My conclusions based on my experience and scientific analysis:

*With this recipe and volumes, even if you had sparged, you should have expected only about 80% brewhouse efficiency and OG 1.047 (12.2 Brix), not 88% and 1.052 (13.3 Brix). So, your initial expectations were a bit lofty and unreasonable, especially considering no sparge (you didn't sparge, right?). What tipped me off to this was only 9 lb malts in a 5.5-gallon batch ---- the norm for a 1.052 beer, gut feel, should be more like 11 lb or something in that neighborhood. Just 9 lb is not enough malt for that gravity, unless you crush really well, sparge a lot, boil longer, etc.

*Wheat kernels are smaller in size than barley kernels. As such, if you achieved a good crush of the barley malt at say 80% awesomeness as I would have expected per above, but only cracked the wheat kernels about 50% of the way (just an inadequate crush), this would give an OG 1.039, which is about exactly what you got. So I think the use of wheat is almost certainly partially to blame here. If you'd gone with 100% barley, this might not have happened or symptoms would not be as bad. Need to set the mill tighter if you're using wheat, or double-crush or something to help crack the wheat better.

*Your refractometer or hydrometer must be out of calibration. Test both in plain water at 22 C and see if they read 1.000. If not, well, there's that.

*Your pH meter might also be reading a bit high. With the RO water, salts and acid additions that you used, I would have expected a mash pH of about 5.3, so I'm surprised that it was 5.5. Could be less than awesome RO water quality with too much impurities? might be time to change the membranes? I don't know. Think on this a bit.

Hope this gives you some good answers and things to consider. Cheers. And don't thank me, I enjoy doing stuff like this, it's "fun".

Ah, yes. Wheat malt. That can cause a problem if not milling those kernels tighter. Great analysis.

 

[Epos7]

For batch sparge, I set my mill to .033 and get 80% efficiency. I think you need to go tighter on your gap. From everything I've read, you should mill with a tighter gap for BIAB than you would a traditional set up assuming no recirculation. I read the description of crushed grain as "coarse corn meal". Your second picture seems to have some grains somewhat intact.

0.045" is a typical setting, so I was thinking my setting of 0.035" was tighter than normal. I'll see if I can go tighter next time, although I'm not sure if my drill can handle it.

 

[Epos7]

*With this recipe and volumes, even if you had sparged, you should have expected only about 80% brewhouse efficiency and OG 1.047 (12.2 Brix), not 88% and 1.052 (13.3 Brix). So, your initial expectations were a bit lofty and unreasonable, especially considering no sparge (you didn't sparge, right?). What tipped me off to this was only 9 lb malts in a 5.5-gallon batch ---- the norm for a 1.052 beer, gut feel, should be more like 11 lb or something in that neighborhood. Just 9 lb is not enough malt for that gravity, unless you crush really well, sparge a lot, boil longer, etc.

Nope, no sparge, just squeezed the bag.

*Wheat kernels are smaller in size than barley kernels. As such, if you achieved a good crush of the barley malt at say 80% awesomeness as I would have expected per above, but only cracked the wheat kernels about 50% of the way (just an inadequate crush), this would give an OG 1.039, which is about exactly what you got. So I think the use of wheat is almost certainly partially to blame here. If you'd gone with 100% barley, this might not have happened or symptoms would not be as bad. Need to set the mill tighter if you're using wheat, or double-crush or something to help crack the wheat better.

OK so maybe go even tighter on the mill gap, somewhere in the 0.025-0.030". I was hoping I wouldn't need to double crush with this mill, but that's something I can try too.

*Your refractometer or hydrometer must be out of calibration. Test both in plain water at 22 C and see if they read 1.000. If not, well, there's that.

I calibrate my refractometer with distilled water with each use, it reads 0. I just put my hydrometer in tap water, and it read a little over 1, which is ironic since I bought it to see if my refractometer was giving bad reading.

*Your pH meter might also be reading a bit high. With the RO water, salts and acid additions that you used, I would have expected a mash pH of about 5.3, so I'm surprised that it was 5.5. Could be less than awesome RO water quality with too much impurities? might be time to change the membranes? I don't know. Think on this a bit.

The RO filter is only a few months old, and TDS of water out of the filter is in the range of 10-20ppm. Since I have a countertop RO filter, I have to plan ahead to fill my kettle. I usually do this a day or two in advance. This time around I noticed that after RO water had been sitting in my kettle with the lid on for a couple of days, its ppm was over 100. It's a little bit of a mystery as to where these extra dissolved solids are coming from, but it could explain the pH discrepancy.

Hope this gives you some good answers and things to consider. Cheers. And don't thank me, I enjoy doing stuff like this, it's "fun".

Well, thanks anyway, I appreciate it.

 

[Epos7]

You did nail the starting strike water in the brew I looked at before. I ran that recipe through the BIABacus, which I use. I mentioned kettle efficiency, because that's all we have to go on from you. If you are adding the entire contents of the kettle after the brew into the fermenter, which is okay, you could have as much as 3/4 gallon of trub in there. Brewhouse efficiency is not known until all the loses are accounted for.

If you are withholding the trub from the fermenter, then we are not getting the full picture of the loses, volumes.

I'm not really getting much trub in the kettle, so I'm just transferring until I fill the fermenter. Last time I had almost nothing left in the kettle, this time around I had half a gallon left over.

 

[Epos7]

I'm starting to wonder if my stainless steel kettle might be leaching some metal ions into my brewing water that are interfering with the starch conversion process.

Last time I brewed I noticed that after my RO water had been sitting in the kettle for a little while, TDS levels went through the roof. I thought I had cleaned the kettle pretty well, but wasn't ready to rule out some stubborn residue causing the increase.

After that last batch, I decided to conduct an experiment. I cleaned the kettle with soap and water, rinsed, did a PBW soak, scrubbed some more, and rinsed thoroughly with a high pressure hose. I also cleaned out all the fittings. I'm positive it was 100% clean. I then filled it with five gallons of reverse osmosis water. My TDS meter read 3ppm after the kettle had collected five gallons of RO water, a process that takes several hours with my filter. I then left the kettle with the lid on for a little under two days, and checked it again this morning. It now reads 320ppm.

I don't know if it's possible for metal ions to interfere with the starch conversion process, but I know something is leaching into my water.

 

[Epos7]

If it is iron leaching into my brewing water from my kettle, it could explain my poor conversion efficiency:

http://www.mbaa.com/meetings/distri...ingPresentationBrewingRawMaterialsQuality.pdf

Iron levels should be low to avoid incomplete saccharification

 

[wilserbrewer]

I'm starting to wonder if my stainless steel kettle might be leaching some metal ions into my brewing water ....

I wouldn't have thought that possible, but I will curiously wait for someone more knowledgeable to comment.

 

[dmtaylor]

Wow, this is indeed unexpected. I'm not smart enough to answer this one either.

 

[Epos7]

I may have spoken too soon. While I have been able to reproduce the 300+ ppm measurements of the RO water stored for several days in my kettle, I've also started getting readings in the 5-10ppm range, which is what I would expect for RO water. At this point I think it's likely the high readings I am seeing are instrumentation error, and I don't have excess iron or anything in my brewing water. That points to mill gap as still being the culprit for my poor efficiency.

 

[cegan09]

I'm not saying that gap isn't an issue, however I somewhat fixed my poor numbers by rinsing the grains after pulling the bag. I have missed every OG number on every brew day so far, and have some bad numbers. Crush is good, I stir like mad, stir several times during mash, squeeze the crap out of the bag, etc. Still miss.

Last brew I took a 5 gallon bucket, drilled a ton of holes in the bottom, then set that into my 6.5gallon bottling bucket. Pulled the bag at the end of the mash, drained, squeezed some, then put the bag into this bucket setup. I then poured a gallon of clean water over the grains using a pasta strainer to help "spread" it. Water was at mash temp. I made sure i had this recorded in beer smith to make sure my volumes were right. I then squeezed the crap out of the bag again and drained this extra gallon into the kettle. I nailed my numbers that brew. This may be something to consider. I know many people claim they don't need any type of sparge or rinse, but I couldn't get there. Might be worth considering if messing with the gap doesn't gain you anything.

 

[wilserbrewer]

Wheat and rye are hard little berries, crush more!

Some actually keep a corona mill for dedicated wheat and rye milling.

 

[dmtaylor]

I'm not saying that gap isn't an issue, however I somewhat fixed my poor numbers by rinsing the grains after pulling the bag.... poured a gallon of clean water over the grains using a pasta strainer to help "spread" it. Water was at mash temp. I made sure i had this recorded in beer smith to make sure my volumes were right. I then squeezed the crap out of the bag again and drained this extra gallon into the kettle. I nailed my numbers that brew. This may be something to consider. I know many people claim they don't need any type of sparge or rinse, but I couldn't get there. Might be worth considering if messing with the gap doesn't gain you anything.

Yep, sparging will help, especially as your desired gravity approaches 1.060-1.065 or beyond. Above that point, it's really difficult to achieve decent efficiency without a sparge -- I don't care how hard you squeeze. I don't squeeze at all ever. I just sparge. It's quick and easy and very effective.

 

[Epos7]

After giving it some more thought, I've concluded that there are likely four variables that affect the final crush: roller diameter, mill gap, roller type (knurled or helical slotted), and roller speed.

With my mill set at 0.035" my drill is working pretty hard, and thus not spinning all that fast. I'm hypothesizing that a slower mill speed may be more likely to crush the grains, and a higher mill speed may be more likely to tear them. When taking the other variables into account, especially the difference between knurled and helical rollers, it seems likely that a 0.035" gap on one mill produces a significantly different crush than a 0.035" gap on another mill.

With this is mind, I think for my next batch I'll try setting the gap to 0.025" and see if my drill can handle it. If not I'll try 0.030". In the future I intend to purchase a direct drive motor to power the mill, which should help by maintaining a consistent roller speed. I'm working on designing a small table to accommodate this at the moment. Until then I'll try a narrower gap with my drill and see where that gets me. If I don't start to see some significant improvements, I'll look into adding a sparge step.

 

[wilserbrewer]

After giving it some more thought,.

Stop thinking and crush more lol, just kidding. I would try and hold .025 even if it means narrowing the mill feed even temporarily with a little duct tape.....

Perhaps all barley malt, no wheat as well.....

cheers!