Scaling efficiency down alters the grain proportions

I had always thought that any increase/decrease in grain would be relatively proportional for all grains. However, I have noticed my beersmith efficiency calculations seem funky on more a few occasions. Let me elaborate.

Let's use this recipe as an example (personal favorite.. brew this if you haven't tried it yet): http://www.homebrewtalk.com/f66/cascades-orange-pale-ale-84558/

The recipe assumes 68% efficiency, and the grain bill is:

9lbs Maris Otter (81.8% grain bill)
1lbs Vienna Malt (9.1% grain bill)
1lbs Crystal 20L (9.1% grain bill)


My method of brewing is no-spage, so, if I adjust my efficiency to about 50% I usually hit all of my numbers. When I adjust the above recipe in Beersmith to 50% efficiency using the 'Scale Recipe' function, the recommended grain bill is:

13lbs 1oz Maris Otter (88% grain bill)
1lbs 7oz Vienna Malt (9.8% grain bill)
5.3 oz Crystal 20L (2.2% grain bill)


I expect that the base grain would increase the most, but I can't figure out why the Vienna Malt increases by 7oz, and the Crystal 20L decreases by 11oz. If I am expecting a lower efficiency and therefore less output per lbs of grain, why would my recipe conversion for some grains go from 1lbs to only 5oz (over 50% drop)? I would think it would increase at the same rate as the Vienna malt... or at LEAST stay the same at 1lbs.

So what am I missing here?  ???

Hi,
  The program (by default) will try to match the color and IBU values of the original recipe.  If you change efficiency without changing the equipment profile, this will result in some small changes in the proportion of ingredients to match the original color and IBU levels.  I think that is what you are seeing here.

  For instance you can really get some odd numbers if you scale a recipe batch size without changing the other equipment settings.

  If you have a particular case that is bad - email the BSMX file for the recipe (right click then export selected on that recipe) and I'll take a look at it!

Brad

Interesting, so a pound of crystal in 10 gallons would not be the same color as half a pound in 5 gallons?

BeerSmith said:

Hi,
  The program (by default) will try to match the color and IBU values of the original recipe.  If you change efficiency without changing the equipment profile, this will result in some small changes in the proportion of ingredients to match the original color and IBU levels.  I think that is what you are seeing here.

  For instance you can really get some odd numbers if you scale a recipe batch size without changing the other equipment settings.

  If you have a particular case that is bad - email the BSMX file for the recipe (right click then export selected on that recipe) and I'll take a look at it!

Brad

Click to expand...

This is what is happening. I am not changing the equipment profile, even though the original recipe is not made on my equipment.

Is there a default equipment profile that people use when the post recipes?

I thought that most people would enter recipes into beersmith to match the recipes original gravity, ibu, etc, and then scale to their particular setup. I did not consider that the original recipe should have a different equipment profile.