Originally Posted by EyePeeA
So, the partial mash must have contributed about: 490 - 333.81 = 156.19 gravity points
Calculating efficiency is the sugars extracted from the grain divided by the potential amount of sugars in the grain * 100:
In other words: (Sugars extracted / Sugar potential) * 100
Sugars extracted is easy to calculate: volume of wort * (OG - 1.000)
Sugar potential depends on the grain, most base malts are about 1.036, meaning at 100% efficiency 36 gp would be extracted. So, the potential of each of your grains multiplied by the weight of the grains used.
Sugars extracted = 1.050 gravity sample at 110 degrees is 1.057 with the correction factor. You said you think the absorption was more than .15, maybe .25 gallons.
So, 2.4 gallons - .25 gallons = 2.15 total gallons: 2.15 * 57 = 122.55 gravity points extracted (sugars extracted)
Sugar potential, I usually rely on beersmith for this, but I'll give it a try. I'll estimate 36 points for the 2 row, 38 for the wheat malt, and 34 for the 10L crystal malt. source: Designing Great Beers by Ray Daniels
2 row = 36 * 4 = 144
Wheat = 38 + (6/16 * 38) = 52.25
10L Crystal = (11/16 * 34) = 23.275
Sugar Potential = 144 + 52.25 + 23.275 = about 219.53
Efficiency = 122.55 / 219.53 * 100 = about 56%
Some general observations:
1. I'm not sure your mash OG is accurate. You don't know the exact temperature for the hydrometer correction factor and you don't know the exact volume. In the future, take the sample cool it in the fridge, not the gravity, then you can return the sample to the boil.
2. There's a discrepancy between your actual gravity reading and what our calculations predicted your partial mash gravity to be, 156.19 vs 122.55. In my opinion, this is probably because your volumes are off and/or your hydrometer is off.
3. Don't be discouraged by the low efficiency. Keep brewing and take very good notes during the brew process. I make a checklist before I brew and write down my notes next to the checklist item. That's helped me improve my process. Also, find a way to approximate your volumes (a long spoon with markings, etc.)
I hope this helps. PS - Buy brewing software