Conversion Efficiency dropping,dropping, dropping...

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sundog14

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Lately (last 4 to 5 batches) I've seen my conversion efficiency dropping from almost 80% down to a little below 60%. I measure pre-boil and use volume and SG along with potential PPG to determine my conversion efficiency. All procedures have remained the same except that about 3 batches ago I reduced the gap on my crusher by ~ .005". I read texasbrewer73's post and feel that I've got most of my bases covered there given the equipment that I have. The variable that I'm focusing on and have not seen covered is grain (malt) freshness. The base malt that I'm using (organic 2-row) is from a 50# bag and is 6+ months old. I'm wondering if it's losing some of it's potential sugars?
Any thoughts/comments?
Thanks, Tom
 

cubalz

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Just for clarification: Are you saying that your efficiency is dropping that much while doing the same recipe using the same equipment, following the same process? My money says that you changed on thing or a couple of things that has caused the drop. My recommendation is to go through your brew notes and identify the changes, revert back to your normal methods on a proven recipe you are done before with repeatable success and check your efficiency. Check the results. Accurate and detailed brew notes are key.
 

Gavin C

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Lately (last 4 to 5 batches) I've seen my conversion efficiency dropping from almost 80% down to a little below 60%. I measure pre-boil and use volume and SG along with potential PPG to determine my conversion efficiency. All procedures have remained the same except that about 3 batches ago I reduced the gap on my crusher by ~ .005". I read texasbrewer73's post and feel that I've got most of my bases covered there given the equipment that I have. The variable that I'm focusing on and have not seen covered is grain (malt) freshness. The base malt that I'm using (organic 2-row) is from a 50# bag and is 6+ months old. I'm wondering if it's losing some of it's potential sugars?
Any thoughts/comments?
Thanks, Tom
You are describing measuring mash efficiency.

Mash efficiency = Lautering efficiency x Conversion efficiency

Conversion efficiency = Mash efficiency/ Lautering efficiency

More on mash and brewhouse efficiency in my signature below.
 
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sundog14

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Thank you for the replies.
Other than changing the roller gap (tighter), I don't think I have changed any of my procedures. Yes, they were different recipes, but I have seen the reduction across-the-board. i use your method for calculating conversion efficiency with the exception that I do not allow for the temperature/volume adjustment. my calculation method is the same each time. the aging of the malt is the only other factor that I can think of. Briesse states that the malt will have reduced sugar content after ~ 6 months in storage. I know that mine is older than that, possibly 9+ months.
I was quite happy when I was averaging mid-70's for efficiency on a regular basis. To adjust for lower conversion efficiency I have increased boil time and/or added a sugar (typically honey as I'm a beekeeper) at end of boil.
FWIW, I don;t deal with brewhouse efficiency anymore.
 
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Double check that roller gap again. That's the one thing you said you messed with, and it can definitely make a difference. Maybe you didn't get one side tightened back down enough, or your measurement was off.
 

mblanks2

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the aging of the malt is the only other factor that I can think of. Briesse states that the malt will have reduced sugar content after ~ 6 months in storage. I know that mine is older than that, possibly 9+ months
I've had malt up to 18 months, Breiss and other brands with no decrease in efficiency.
Double check your roller gap. What is the gap anyway?
 

dmtaylor

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Have your OG goals been increasing while your efficiency has decreased? There is a definite inverse proportional relationship between desired OG and efficiency.
 

pricelessbrewing

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As Gavin said, you're describing mash efficiency.

Conversion efficiency should be in the 90-95% range for most brewers. Low conversion efficiencies might be in the 80-90% range.

Read my blog post on the differences in each efficiency, and how to troubleshootand Gavins thread, then hopefully you have notes to determine where your issue is, conversion (usually grain crush), lauter (bad sparge practices), or mash/brewhouse losses.
 

hottpeper13

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When changing malts you need to look at the analysis to get the course grind,that will tell you if the grain is an issue. The barley plant needs a lot of nitrogen and organic might not be at the top. Also look at the modification, you might need a protein rest to get at some of the starches.
 
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sundog14

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Thanks for all the replies.
kcbrewer: I have a Barley Crusher and reduced the gap from 0.048" to 0.043"
mblank2: 18 months seems like a long time....
dmtaylor: My OG goal has remained the same; to be with a few points of predicted.
priceless brewing: have not had time to read all your article, but am curious about the statement: "Post boil gravity and volume gives the boil off rate and mash efficiency." Isn't mash efficiency measured before boil?
hottpeppers13: I have pretty much kept my mash schedule uniform. Perhaps I will adjust it. But I was hitting my target OG with my typical mash schedule....
 

doug293cz

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priceless brewing: have not had time to read all your article, but am curious about the statement: "Post boil gravity and volume gives the boil off rate and mash efficiency." Isn't mash efficiency measured before boil?

....
Mash efficiency is calculated as:
Sugar_in_Boil_Kettle / Max_Potential_Sugar
Unless you add sugar during the boil (or have a huge spill/boil over), the sugar in the BK will be the same before and after the boil. The amount of sugar in the BK is determined from the volume in the BK, and the SG at that volume. So, you can use either pre-boil volume and SG, or post-boil volume and SG to determine mash efficiency (as long as you didn't add sugar during the boil.)

Brew on :mug:
 
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sundog14

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Hello Dave and Doug,
Water source has not changed. I use local tap water that is actually RO....yes, all of our city water is RO. I was initially anxious about this water but have found that it is great for most brewing. i only add salts (CaCl and/or gypsum) for some low gravity beers to lower pH. For these batches the pH has been ~ 5.3 to 5.4 and I'm happy with that. As far as I can recall, tools have remained the same.
I'm still a bit confused about "efficiency" and for now will determine it for pre-boil as this seems to eliminate some post-boil variables. At some point I will look at post-boil.
 
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Take a pic of your crush next time and post it, or go run a 1/2 lb through it if you have some grain on hand. And try using 2 thermometers to verify temp is what you think it is during your next mash.

I gap my mill with a credit card and hit 75-80% efficiency with my eBIAB setup, and can get a little higher on my 2 vessel gas setup. It's lower on both systems the bigger the beer is though.
 

pricelessbrewing

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Hello Dave and Doug,
I'm still a bit confused about "efficiency" and for now will determine it for pre-boil as this seems to eliminate some post-boil variables. At some point I will look at post-boil.
I don't know much about water chemistry unfortunately. I just do what bru'n water tells me.

Regarding "efficiency", that's why I made my post. There's 4-6 different kinds of efficiencies, and you learn a little bit about your system from calculating each one, yet no one ever seems to say which they're talking about. The rule of thumb is that, unless otherwise specified, it's probably the brewhouse efficiency (volume and gravity of wort into fermenter)

Re: Preboil/postboil mash efficiency. I find it best to use the preboil, before hops are added. Measuring your volume with hops is going to inflate your volume a bit from the displacement of the hops as they absorb some of the wort and throw off your calculation.

@doug293cz have you read it? Any comments, or things I should clarify/simplify further?
 

doug293cz

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I don't know much about water chemistry unfortunately. I just do what bru'n water tells me.

Regarding "efficiency", that's why I made my post. There's 4-6 different kinds of efficiencies, and you learn a little bit about your system from calculating each one, yet no one ever seems to say which they're talking about. The rule of thumb is that, unless otherwise specified, it's probably the brewhouse efficiency (volume and gravity of wort into fermenter)

Re: Preboil/postboil mash efficiency. I find it best to use the preboil, before hops are added. Measuring your volume with hops is going to inflate your volume a bit from the displacement of the hops as they absorb some of the wort and throw off your calculation.

@doug293cz have you read it? Any comments, or things I should clarify/simplify further?
I didn't think about the volume that the hops add to the total BK volume, so agree that pre-boil mash efficiency calcs will be more accurate. I don't think the water absorption of the hops matters a wit w.r.t. mash efficiency, just the volume added by the hops. Hop absorption will affect packaged efficiency, and brewhouse efficiency if all kettle trub is not dumped in the fermenter.

Good article. I need to read the article again, and then I'll put my comments together.

Brew on :mug:
 
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