[Lazy Ant Brewing]

On previous brewing, I calculated my mash efficiency to be 75%.

I wish to work with a recipe BYO magazine that lists Extract Efficiency at 65% under the recipe standardization headline. 

What is the easiest way to do this calculation?

If the recipe begins with:

8.5 lbs pale ale malt
9 oz. roasted barley

What should my values be for those, and how would I derive them?

Could it be as simple as dividing the 65 by 75 and multiplying the result times each of the fermentible ingredients?

Thanks in advance for your help.

[Stevie]

I typically adjust the base grains only, but yes your formula works.

[GS]

I plug in a recipe exactly as it is written. If the brew house efficency is 65%, I leave it alone.
 If not, I take note of the grain percentages in the original recipe, change the brewhouse efficiency in Brewers Friend, then adjust the grain bill to match the original percentages. Problem solved.

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[Stevie]

That doesn't always work. Let's say you have a recipe written for 75% efficiency. 9lb 2-row and 1lb c40. Convert that to 50% efficiency and you will end up with 1.5lb crystal malt and a much darker beer. Converting isn't always perfectly linear.

[GS]

If I had to convert to 50% efficiency (because that's what my process gives me), the first thing I would do is take a look at my process, not grain percentages.

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[Stevie]

If I had to convert to 50% efficiency (because that's what my process gives me), the first thing I would do is take a look at my process, not grain percentages.

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That's cool, just calling out that it doesn't always work using scenarios with simple math.

[denny]

That doesn't always work. Let's say you have a recipe written for 75% efficiency. 9lb 2-row and 1lb c40. Convert that to 50% efficiency and you will end up with 1.5lb crystal malt and a much darker beer. Converting isn't always perfectly linear.

Wouldn't the increase in pale malt balance out the color increase from the crystal?

ETA:  Just ran your example through Promash.  Decreasing the efficiency from 75% to 50% the color remained the same.

[Stevie]

Did you also increase the grain by 50% to compensate?

Per Beersmith.

90/10 at 1.055 75% efficiency (10lbs total) is 8 SRM. 90/10 at 1.055 50% efficiency (15lbs total grain) 10.6 SRM

The above example is a simple example to show there is a difference. The difference is noticeable with darker malts at relatively small variances. Not to mention the flavor differences caused by larger amounts of specialty malts.

90/7/3 - 2row/40/500 patent - 75% efficiency = 18.5. 70% = 19.4. 60% = 21.5

One can do whatever works, just should understand that it isn't a perfect linear scale.

[denny]

Did you also increase the grain by 50% to compensate?

Per Beersmith.

90/10 at 1.055 75% efficiency (10lbs total) is 8 SRM. 90/10 at 1.055 50% efficiency (15lbs total grain) 10.6 SRM

The above example is a simple example to show there is a difference. The difference is noticeable with darker malts at relatively small variances. Not to mention the flavor differences caused by larger amounts of specialty malts.

90/7/3 - 2row/40/500 patent - 75% efficiency = 18.5. 70% = 19.4. 60% = 21.5

One can do whatever works, just should understand that it isn't a perfect linear scale.

Yep, I increased the grain.

[Stevie]

The something is up with promash. Increasing the amount of a dark grain will change the color if the same volume of water is used.

[denny]

The something is up with promash. Increasing the amount of a dark grain will change the color if the same volume of water is used.

But if you also change the amount of a lighter grain so the ratio remains the same?

[denny]

The something is up with promash. Increasing the amount of a dark grain will change the color if the same volume of water is used.

Or Beersmith....

[Stevie]

The something is up with promash. Increasing the amount of a dark grain will change the color if the same volume of water is used.

But if you also change the amount of a lighter grain so the ratio remains the same?

No, because the amount of color is not related to efficiency of conversion and even affected by base malts.

Easy examples
100% 2L 2-row - 10lbs at 75% 3.4 SRM, 12.5lbs at 60% 4 SRM
100% 10L Munich - 10lbs at 75% 10.3 SRM, 12.5lbs at 60% 12 SRM

Again, I'm just pointing out that it isn't a simple linear equation to scale every recipe. There is same fiddling that needs to be done.

[Stevie]

The something is up with promash. Increasing the amount of a dark grain will change the color if the same volume of water is used.

Or Beersmith....

Touché

If I cared enough to try to remember the math, I'd show it by hand as well.

[hopfenundmalz]

A local pro said that the color in Promash is not right. I usually don't care enough to calculate by hand.