What's Your Typical Conversion Efficiency?

[Epos7]

I received a reply from Brewer's Friend today. They said they have spent some time looking over their formulas, and believe everything to be correct.

They provided their conversion efficiency formula as:

CE = 100 * Plato_measured * (100 - Plato_max) / (Plato_max * (100 - Plato_measured))

Where:

Plato_max = 100 * extract_weight / (volume_liters + extract_weight); (extract weight is measured in KG)

They also noted that they visited the Breiss website, referencing this link:

http://blog.brewingwithbriess.com/understanding-a-malt-analysis/

and stated "optimal moisture between 3-6% because of spoilage & crushing problems with moist grain, but it-is-what-it-is, I didn't see any product offered based upon moisture content."

I'm not too sure what to make of that.

They closed by saying their calculation is based on the amount of extract and pre-boil wort volume, and that I should check my volumes.

I'm glad they finally replied, although I'm somewhat confused by their response. I think I will take their advice and check the volume markings on my kettle for accuracy, but they weren't able to explain why their Brewhouse Efficiency calculator and Brew Session tool output a different result.

The end result seems to be if you use Brewer's Friend to calculate conversion efficiency, you can't compare your result to other brewers using different calculators, and you can't compare results from the Brewer's Friend Brewhouse Efficiency Calculator to their own Brew Session tool.

 

[Epos7]

I've been meaning to post some info on my last two brews, completed two weeks ago.

Brew #1 - Zombie Dust Pale Ale
10.24lb Great Western organic 2-row
1.02lb American Munich 10L
0.42lb German carafoam
0.42lb American crystal 60L
0.42lb German melanoidin
Total grain bill - 12.52lb

Mashed in 8.22 gallons of water measured at 68F. Mash temp 152F, held consistent throughout the 60 minute mash by refiring the burner three times. Five minutes of stirring at mash-in, as well as five minutes of stirring every time the burner was refired. That means I spent 20 minutes stirring during the 60 minute mash.

10.3 brix on my refractometer at the end of the mash. 10.9 brix on my refractometer after squeezing the bag.

Brew #2 - Mosaic Honey Wheat
4lb Great Western organic 2-row
4lb American organic wheat
1lb Canadian honey malt
Total grain bill - 9lb

Mashed in 7.83 gallons of water measured at 157F (I didn't quite have enough RO water ready to go, so I started heating what I had and added to it before mashing in). Mashed at 152F for 60 minutes. Again, I refired the burner three times to maintain my mash temp, and for this one I spent 15-20 minutes stirring during the 60 minute mash.

8.8 brix on my refractometer at the end of the mash. 9.0 brix after squeezing the bag.

Brewer's Friend gives me 79% conversion efficiency for Brew #1, and 82% for Brew #2. I still need to learn to use a different calculator, but I'm guessing that puts me at ~84% and ~87% respectively when accounting for grain moisture content.

I've now brewed seven times with this mill, and cannot seem to get good conversion efficiency. Conversion efficiency did go up as I narrowed the gap, but I hit a wall when I couldn't make the gap any narrower.

The one last thing I plan to check is ensuring that my kettle volumes are accurate, but given that I'm seeing more sugar in the wort post-squeeze, that tells me conversion isn't completing, which again points to the mill.

I don't think the helical rollers produce a fine enough crush to achieve good conversion efficiency. I think I've given this mill a very fair chance, and plan to contact the manufacturer to see if I can exchange it for a mill with knurled rollers.

 

[doug293cz]

I've been meaning to post some info on my last two brews, completed two weeks ago.

Brew #1 - Zombie Dust Pale Ale
10.24lb Great Western organic 2-row
1.02lb American Munich 10L
0.42lb German carafoam
0.42lb American crystal 60L
0.42lb German melanoidin
Total grain bill - 12.52lb

Mashed in 8.22 gallons of water measured at 68F. Mash temp 152F, held consistent throughout the 60 minute mash by refiring the burner three times. Five minutes of stirring at mash-in, as well as five minutes of stirring every time the burner was refired. That means I spent 20 minutes stirring during the 60 minute mash.

10.3 brix on my refractometer at the end of the mash. 10.9 brix on my refractometer after squeezing the bag.

Brew #2 - Mosaic Honey Wheat
4lb Great Western organic 2-row
4lb American organic wheat
1lb Canadian honey malt
Total grain bill - 9lb

Mashed in 7.83 gallons of water measured at 157F (I didn't quite have enough RO water ready to go, so I started heating what I had and added to it before mashing in). Mashed at 152F for 60 minutes. Again, I refired the burner three times to maintain my mash temp, and for this one I spent 15-20 minutes stirring during the 60 minute mash.

8.8 brix on my refractometer at the end of the mash. 9.0 brix after squeezing the bag.

Brewer's Friend gives me 79% conversion efficiency for Brew #1, and 82% for Brew #2. I still need to learn to use a different calculator, but I'm guessing that puts me at ~84% and ~87% respectively when accounting for grain moisture content.

I've now brewed seven times with this mill, and cannot seem to get good conversion efficiency. Conversion efficiency did go up as I narrowed the gap, but I hit a wall when I couldn't make the gap any narrower.

The one last thing I plan to check is ensuring that my kettle volumes are accurate, but given that I'm seeing more sugar in the wort post-squeeze, that tells me conversion isn't completing, which again points to the mill.

I don't think the helical rollers produce a fine enough crush to achieve good conversion efficiency. I think I've given this mill a very fair chance, and plan to contact the manufacturer to see if I can exchange it for a mill with knurled rollers.

Are you measuring the Brix of the total wort volume after squeezing, or just the squeezed out volume? If the total volume, are you stirring the wort well before taking the measurement?

Brew on

 

[doug293cz]

Math below. Proceed at your own risk.

I received a reply from Brewer's Friend today. They said they have spent some time looking over their formulas, and believe everything to be correct.

They provided their conversion efficiency formula as:

CE = 100 * Plato_measured * (100 - Plato_max) / (Plato_max * (100 - Plato_measured))

Where:

Plato_max = 100 * extract_weight / (volume_liters + extract_weight); (extract weight is measured in KG)

They also noted that they visited the Breiss website, referencing this link:

Understanding a Malt Analysis - Brewing With Briess

and stated "optimal moisture between 3-6% because of spoilage & crushing problems with moist grain, but it-is-what-it-is, I didn't see any product offered based upon moisture content."

I'm not too sure what to make of that.

They closed by saying their calculation is based on the amount of extract and pre-boil wort volume, and that I should check my volumes.

I'm glad they finally replied, although I'm somewhat confused by their response. I think I will take their advice and check the volume markings on my kettle for accuracy, but they weren't able to explain why their Brewhouse Efficiency calculator and Brew Session tool output a different result.

The end result seems to be if you use Brewer's Friend to calculate conversion efficiency, you can't compare your result to other brewers using different calculators, and you can't compare results from the Brewer's Friend Brewhouse Efficiency Calculator to their own Brew Session tool.

Since °Plato is defined as weight percent extract in the wort, the equation for Plato_Max is more properly written:

Plato_Max = 100°P * Max_Extract_Weight / (Water_Weight + Max_Extract_Weight)​

Where Water_Weight is the weight of all the water in the mash​

By using the water weight, the units used for weight do not matter. Water @ 68°F has a density of 8.3304 lb/gal, or 0.9982 kg/L (water is only 1.0000 kg/L @ 4°C.)

The equation for Max_Extract_Weight is:

Max_Extract_Weight = Dry_Grain_Weight * Fine_Grind_Dry_Extract_Potential / 100%​

Where Fine_Grind_Dry_Extract_Potential is in percent​

If potential is given in SG, you can convert to percent using the following equation:

Fine_Grind_Dry_Extract_Potential (%) = 100% * 1000 * (SG_Potential - 1) / 46.173​

If potential is given in PPG, then the equation to convert to % is:

Fine_Grind_Dry_Extract_Potential (%) = 100% * PPG / 46.173​

Now, normally grain weights are "As Is" meaning the weight includes the water weight absorbed in the grain (typically around 4% by weight.) To convert As_Is_Grain_Weight to Dry_Grain_Weight, use the following equation:

Dry_Grain_Weight = As_Is_Grain_Weight * (1 - Moisture Content / 100%)​

Where Moisture_Content is given in percent​

Since you need to use Dry_Grain_Weight to calculate Max_Extract_Weight, it is an error to use As_Is_Grain_Weight without making a moisture content correction to calculate Max_Extract_Potential, and this is the error that one of the BrewersFriend Conversion Efficiency calculators makes. I haven't figured out exactly what the error is in the other BrewersFriend calculator that purports to calculate Conversion Efficiency.

The standard definition of any efficiency is:

Efficiency (%) = 100% * Actual / Maximum​

For Conversion Efficiency this becomes:

Conversion_Efficiency = 100% * Actual_Extract_Weight / Max_Extract_Weight​

We can rearrange the ˚Plato equation as follows:

°Plato = 100°P * Extract_Weight / (Water_Weight + Extract_Weight)​

°Plato * (Water_Weight + Extract_Weight) = 100°P * Extract_Weight​

°Plato * Water_Weight + °Plato * Extract_Weight = 100°P * Extract_Weight​

°Plato * Water_Weight = 100°P * Extract_Weight - °Plato * Extract_Weight​

°Plato * Water_Weight = (100°P - °Plato) * Extract_Weight​

Extract_Weight = °Plato * Water_Weight / (100°P - °Plato)​

Now if we substitute the final equation above into the Conversion_Efficiency equation, we get:

Conversion_Efficiency = 100% * (Actual_°P * Water_Wt / (100°P - Actual_°P)) / (Max_˚P * Water_Wt / (100°P - Max_°P))​

Conversion_Efficiency = 100% * Actual_°P * Water_Wt * (100°P - Max_°P) / (Max_°P * Water_Wt * (100°P - Actual_°P))​

And since Water_Wt is the same for both Max and Actual:​

Conversion_Efficiency = 100% * Actual_°P * (100°P - Max_°P) / (Max_°P * (100°P - Actual_°P))​

Which shows how BrewersFriend's first Conversion_Efficiency equation is derived. But, if you you calculate Max_˚Plato incorrectly, the answer is still crap.

Brew on

 

[Epos7]

Are you measuring the Brix of the total wort volume after squeezing, or just the squeezed out volume? If the total volume, are you stirring the wort well before taking the measurement?

Brew on

Total volume. I'm not stirring the wort after squeezing I suppose, although I'm using a thief, so I'm pulling a sample from about 6" below the surface. My understanding is that with a good crush, conversion should be complete after 60 minutes, so squeezing the bag should only affect wort volume, not brix/sg.

Thanks for the explanation on why BF's conversion efficiency differs. Makes sense to me.

 

[doug293cz]

Total volume. I'm not stirring the wort after squeezing I suppose, although I'm using a thief, so I'm pulling a sample from about 6" below the surface. My understanding is that with a good crush, conversion should be complete after 60 minutes, so squeezing the bag should only affect wort volume, not brix/sg.

Thanks for the explanation on why BF's conversion efficiency differs. Makes sense to me.

Yes, with a fine enough crush, conversion should be complete in less than 60 minutes. With a superfine crush, conversion can be complete in under 30 minutes.

I recommend stirring the wort before taking a measurement. I also don't have an explanation for why SG after squeezing would be higher, other than conversion was continuing in the time before squeezing. I'd be interested if anyone had an alternate explanation that is plausible.

I got a demonstration of the crush effect on National Learn to Homebrew Day. I was doing a BIAB demo at my LHBS. My grain mill has decided to stop working (won't pull grain thru, even tho idle roller turns freely), so I had to use the LHBS's mill. My conversion efficiency dropped from my normal 95%+ to 77 - 78%. Ouch! I normally crush with a gap of 0.016" (checked with feeler gauge), have no idea where the LHBS's mill is set.

Brew on

 

[Epos7]

I also don't have an explanation for why SG after squeezing would be higher, other than conversion was continuing in the time before squeezing. I'd be interested if anyone had an alternate explanation that is plausible.

My brix readings taken at 15 minute intervals throughout the mash show that conversion was still ongoing up to 60 minutes, so I think that's the most likely explanation.

The mill manufacturer has been great, and has agreed to exchange the mill. I almost wonder if they sent me a prototype mill on accident, as they say at the smallest gap setting the mill should only produce flour. That's a much different result that I have been seeing. Maybe one of the prototypes had deeper grooves than the production units, and I was sent that one by accident. Who knows. Anyway, I'm exchanging it for a mill with knurled rollers and am looking forward to seeing what that will do for my conversion efficiency

 

[stever1000]

Math below. Proceed at your own risk.



Since ˚Plato is defined as weight percent extract in the wort, the equation for Plato_Max is more properly written:

Plato_Max = 100˚P * Max_Extract_Weight / (Water_Weight + Max_Extract_Weight)
Where Water_Weight is the weight of all the water in the mash​

By using the water weight, the units used for weight do not matter. Water @ 68˚F has a density of 8.3304 lb/gal, or 0.9982 kg/L (water is only 1.0000 kg/L @ 4˚C.)

The equation for Max_Extract_Weight is:

Max_Extract_Weight = Dry_Grain_Weight * Fine_Grind_Dry_Extract_Potential / 100%
Where Fine_Grind_Dry_Extract_Potential is in percent​

If potential is given in SG, you can convert to percent using the following equation:

Fine_Grind_Dry_Extract_Potential (%) = 100% * 1000 * (SG_Potential - 1) / 46.173​

If potential is given in PPG, then the equation to convert to % is:

Fine_Grind_Dry_Extract_Potential (%) = 100% * PPG / 46.173​

Now, normally grain weights are "As Is" meaning the weight includes the water weight absorbed in the grain (typically around 4% by weight.) To convert As_Is_Grain_Weight to Dry_Grain_Weight, use the following equation:

Dry_Grain_Weight = As_Is_Grain_Weight * (1 - Moisture Content / 100%)
Where Moisture_Content is given in percent​

Since you need to use Dry_Grain_Weight to calculate Max_Extract_Weight, it is an error to use As_Is_Grain_Weight without making a moisture content correction to calculate Max_Extract_Potential, and this is the error that one of the BrewersFriend Conversion Efficiency calculators makes. I haven't figured out exactly what the error is in the other BrewersFriend calculator that purports to calculate Conversion Efficiency.

The standard definition of any efficiency is:

Efficiency (%) = 100% * Actual / Maximum​

For Conversion Efficiency this becomes:

Conversion_Efficiency = 100% * Actual_Extract_Weight / Max_Extract_Weight​

We can rearrange the ˚Plato equation as follows:

˚Plato = 100˚P * Extract_Weight / (Water_Weight + Extract_Weight)
˚Plato * (Water_Weight + Extract_Weight) = 100˚P * Extract_Weight
˚Plato * Water_Weight + ˚Plato * Extract_Weight = 100˚P * Extract_Weight
˚Plato * Water_Weight = 100˚P * Extract_Weight - ˚Plato * Extract_Weight
˚Plato * Water_Weight = (100˚P - ˚Plato) * Extract_Weight
Extract_Weight = ˚Plato * Water_Weight / (100˚P - ˚Plato)​

Now if we substitute the final equation above into the Conversion_Efficiency equation, we get:

Conversion_Efficiency = 100% * (Actual_˚P * Water_Wt / (100˚P - Actual_˚P)) / (Max_˚P * Water_Wt / (100˚P - Max_˚P))
Conversion_Efficiency = 100% * Actual_˚P * Water_Wt * (100˚P - Max_˚P) / (Max_˚P * Water_Wt * (100˚P - Actual_˚P))
And since Water_Wt is the same for both Max and Actual:
Conversion_Efficiency = 100% * Actual_˚P * (100˚P - Max_˚P) / (Max_˚P * (100˚P - Actual_˚P))​

Which shows how BrewersFriend's first Conversion_Efficiency equation is derived. But, if you you calculate Max_˚Plato incorrectly, the answer is still crap.

Brew on

YES!!!! what I have been waiting for
Brewing tonight so this is perfect timing!

 

[stever1000]

If I want to measure the brix every 15mins during mash, what's the best way to store the wort until it cools enough to put it on my refractometer?
every 15mins during a 90min mash would be 6 samples in my fridge/freezer to cool. Does evaporation make a difference (i.e. should I cover with tinfoil?)

 

[doug293cz]

If I want to measure the brix every 15mins during mash, what's the best way to store the wort until it cools enough to put it on my refractometer?
every 15mins during a 90min mash would be 6 samples in my fridge/freezer to cool. Does evaporation make a difference (i.e. should I cover with tinfoil?)

The smaller the sample, the more it will be affected by evaporation (causing high readings.) I use a turkey baster to put a 0.5 - 1 oz sample, place it in a covered glass or ceramic cup, then use an eyedropper to pull that measurement sample. You really don't have to wait for cooling, as the 2 - 3 drop sample on the refract will cool almost instantly.

Brew on

 

[Epos7]

I bought a pack of 50mL beakers on Amazon, I think they cost about $1 each. I take a 30-40mL sample in one of those, cover it with some tin foil, then put it in the fridge for a few minutes until it reaches ~room temperature. I then take readings on all my mash samples at the same time when I'm waiting for my wort to come to a boil. I write the time on each beaker with a sharpie, which is easily removed with rubbing alcohol.

I try to cool the sample quickly, because you're likely to get some grains in there, and if it stays warm conversion will continue, although even at room temperatures it will likely cool enough to stop saccharification within a couple minutes.

 

[TexasWine]

If I want to measure the brix every 15mins during mash, what's the best way to store the wort until it cools enough to put it on my refractometer?
every 15mins during a 90min mash would be 6 samples in my fridge/freezer to cool. Does evaporation make a difference (i.e. should I cover with tinfoil?)

I just bought a huge bag of 3 ml pipettes on Amazon. It doesn't take long for that size sample to cool. I usually just pull it and set the pipette to the side, then go back a couple minutes later to put it on the refractometer.

 

[stever1000]

The smaller the sample, the more it will be affected by evaporation (causing high readings.) I use a turkey baster to put a 0.5 - 1 oz sample, place it in a covered glass or ceramic cup, then use an eyedropper to pull that measurement sample. You really don't have to wait for cooling, as the 2 - 3 drop sample on the refract will cool almost instantly.

Brew on

If it cools almost instantly on the refract, could I take it out of the kettle, drop it directly on the refract, and take the reading a few seconds later (assuming it has had sufficient time to cool within reading limits of the refract)

 

[stever1000]

I just bought a huge bag of 3 ml pipettes on Amazon. It doesn't take long for that size sample to cool. I usually just pull it and set the pipette to the side, then go back a couple minutes later to put it on the refractometer.

This is a great idea... I will look for some pipettes as well

 

[doug293cz]

If it cools almost instantly on the refract, could I take it out of the kettle, drop it directly on the refract, and take the reading a few seconds later (assuming it has had sufficient time to cool within reading limits of the refract)

I lot of folks do just that.

Brew on

 

[stever1000]

I lot of folks do just that.

Brew on

Worked very well for me today between using the pipette and dropping directly on the refract (so I could test 2-3 times of the same sample)

 

[stever1000]

So I adjusted my mill gap to 0.035" and used 4oz of acid malt (recipe called for it) and I got 96% conversion, using Doug's formulas on the previous pages

Whaaaat

 

[Epos7]

So I adjusted my mill gap to 0.035" and used 4oz of acid malt (recipe called for it) and I got 96% conversion, using Doug's formulas on the previous pages

Whaaaat

That's awesome!

Sorry if you mentioned this earlier, but what mill are you using?

 

[stever1000]

That's awesome!

Sorry if you mentioned this earlier, but what mill are you using?

I'm using a 2 roller barley crusher

 

[Epos7]

I'm using a 2 roller barley crusher

Sweet! My replacement knurled rollers from Monster Brewing Hardware are on the way, should be here late next week. I'm hoping I can see a 5-10% jump in conversion efficiency moving away from the rollers with helical cutters. Still holding out hope that Monster will refund the price difference between the two.

 

[bg1414]

reviving old thread. if you fly sparge how/when do you take your first runnings gravity? How does this work in the equations by not having first runnings volume?

 

[doug293cz]

reviving old thread. if you fly sparge how/when do you take your first runnings gravity? How does this work in the equations by not having first runnings volume?

The equations in the OP don't depend in any way on sparge method, nor do they require any volume measurement other than the strike volume. The defining equation for °Plato (°P) is:

°P = 100°P * Wt_of_Extract_in_Wort / (Wt_of_Extract_in_Wort + Wt_of_Water_in_Wort)​

Since Wt_of_Extract_in_Wort + Wt_of_Water_in_Wort) = Total_Wt_of_Wort, °P is just the weight percent of extract in the wort.

The weight of the water in the wort is just the weight of the strike water used in the mash. The equation in the OP assumes you are working in metric (volume in liters, and weight in kilograms.) Since 1 L of water weighs about 1 kg, volume of water in L is approximately equal to the weight of water in kg. The equation in the OP substitutes liters of strike water for kg of strike water. However, water only has a density of 1.000 kg/L at 4°C (39.2°F.) At strike temp (about 160°F) water has a density of 0.977 kg/L. So, for better accuracy, the water density at the volume measurement temp should be used.

If you are using gallons and pounds instead of liters and kilograms, the equations get a little more complicated. One gallon of water weighs 8.3304 lb at 68°F and 8.1545 lb at 160°F. The °P equation becomes the following when using lb and gal:

°P = 100°P * Extract Wt [lb] / (Extract Wt [lb] + Strike Vol [gal] * Water Density [lb/gal]), with the density at volume measurement temp being used​

So, to finally answer your question: the first runnings gravity should be taken after you have assured that the wort in the mash has been well homogenized (the wort has equal extract concentration and SG everywhere), and before any sparge water has mixed with the runnings.

Brew on

​

 

[hezagenius]

Hey @doug293cz

Why wouldn't this formula work for conversion efficiency?

(Measured_Mash_SG - 1)/(Max_SG - 1)?

If you have 10# of grain with a ppg of 37 and you mash with 10 gallons of water, your Max_SG would be 1.037. If you took a reading at the end of your mash and you got Measured_Mash_SG = 1.032, why wouldn't your conversion efficiency be 32/37 = 86.5%?

 

[doug293cz]

Hey @doug293cz

Why wouldn't this formula work for conversion efficiency?

(Measured_Mash_SG - 1)/(Max_SG - 1)?

If you have 10# of grain with a ppg of 37 and you mash with 10 gallons of water, your Max_SG would be 1.037. If you took a reading at the end of your mash and you got Measured_Mash_SG = 1.032, why wouldn't your conversion efficiency be 32/37 = 86.5%?

That's an approximate formula, and the further you are from 100% conversion, the worse the approximation. Don't know exactly how bad the approximation is (but I might run some calcs to figure it out and graph the error.)

If you mash 10 lbs of grain with 37 pts/lb potential with 10 gal of water you will not get an SG of 1.037 @ 100% conversion. Potential is defined as SG that would be obtained by creating 1 gal of wort from 1 lb of grain. Because of the volume taken up by the extract (sugar) in the wort, the volume of the water will be less than 1 gal. Also, potentials are given as dry basis, but grain contains about 4% moisture, so the "as-is" potential is only 96% of the dry potential (and unfortunately, most brewing software does not correct for dry vs. as-is, which makes your conversion efficiency look lower than it is.) If you mash 10 lb of grain with 37 pts/lb dry potential in 10 gal of water, the actual SG @ 100% conversion would be 1.0336. If we ignore the moisture content (assume the 37 pts/lb is as-is basis) the SG @ 100% conversion would be 1.0351.

Brew on

 

[hezagenius]

@doug293cz

So would using Kai's formula of FW_measured/FW_max eliminate the moisture content error?

Built into the FWmax calc is the e_grain term. Why is that 0.8? Why not 0.75 or 0.85?

 

[doug293cz]

@doug293cz

So would using Kai's formula of FW_measured/FW_max eliminate the moisture content error?

Built into the FWmax calc is the e_grain term. Why is that 0.8? Why not 0.75 or 0.85?

If you correct for moisture content when calculating FW_max, then yes. But this formula is still an approximation.

1.037 or 37 pts/lb is equal to 80.13% potential extract. Since most base grains have a potential between 1.036 and 1.038, 80% is a reasonable number to use if you don't have more detailed data on the particular lot of grain.

I don't know why Kai didn't include the moisture correction in his formulas, but did include it in the table. But, it does cause confusion.

Brew on