Originally Posted by Pie_Man
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
You may very well be right on the discrepancy between my figures & measurements. I doubt the mash efficiency was that low considering the rest of the recipe was unchanged. With a projected OG of 1.070 at 75% efficiency and a final reading of 1.069, I don't think it was a mash efficiency problem. More like me not being exact with my measurements. I tried to be accurate, but I see what you're saying here and will try to be more thorough in the future. Thanks for summarizing all of this to paint a clearer picture as well as the extra tips. I appreciate it.