Gravity lower than expected

I brew a mini mash Newcastle Brown Ale today:
2.5 lb 2-row
6 oz Crystal 90L
3 oz Chocolate
3.5 lb Extra pale extract
1 lb Corn sugar
1 oz Fuggle (60 min)
0.25 oz Kent Golding (15 min)
The instructions sheet says that the gravity should be around 1.050, but I measured only 1.032. Did it twice, the same result. Yes, I considered the temperature. And now I am wondering: what lowered my gravity? Could it be a typo on the sheet? Another question is the fermentation temperature. I set it so far for 68 degrees - is it OK?

did you use top off water? you may have a false reading. Did you mash and sparge and what temp?
What yeast for your ferment temp? It has a suggested fermented temp range on the yeast pack.

jonmohno said:

did you use top off water? you may have a false reading. Did you mash and sparge and what temp?
What yeast for your ferment temp? It has a suggested fermented temp range on the yeast pack.

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Yes, I added water. It was about 2 gals of wort after the boil, and I added cool water to make it 5.25 gals. Do you mean I had to check the gravity before adding the water? I mashed at 155 for 45 minutes, then put the bag in the strainer and poured 2 quarts of hot (170) water on it. That's what the instructions called for. The yeast was Dry Windsor Ale, I sprinkled it dry in the carboy, as I did with the other batches. The package doesn't say anything about temperatures, btw.

unionrdr said:

You may not have gotten the chilled wort & top off water mixed thoroughly. It takes quit a bit to mix them. I pour my chilled wort through a fine mesh strainer. It'll strain & aerate it real well,dito with the top off water. Then stir like mad for 5 minutes straight. That seems to work pretty well.

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I don't think this is the problem. When I had all the wort and the water in the carboy, I aerated it with aquarium diffuser attached to a 120 psi compressor Not that I do it always, but my small aquarium compressor suddenly died right when I needed it. Anyway, I adjusted the airflow, and let it blow for a good half hour, and only then checked gravity. I am sure everything mixed well.

bredstein said:

I don't think this is the problem.

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im pretty sure it was the problem. like union mentioned, its pretty difficult to mix water and wort well enough to get an accurate reading, so if you plan on topping off in the future, id just get an OG first and then calculate the batch OG

batch OG = post-boil OG * post-boil volume / batch volume

Today I bottled this beer. It was 0.007, exactly one half of the target gravity per instructions (0.14). What do you guys think contributed to such a low gravity? (The beer tasted nice, by the way).