Unexpectedly High Original Gravity

Saturday I brewed my fourth batch of AG beer, an APA. Based upon my previous batch which had a efficiency of 69%, I estimated this last batch at 70%. The measured original gravity was 1.070, I expected 1.053. I am only doing one gallon batches. This time I performed a double batch sparge, while in the previous batch I only performed one batch sparge. Could this explain the difference in efficiency? I also went to a different homebrew store, so I suppose their grain mill could have contributed as well to the increased efficiency. Also, is this some sort of anomaly-- can I expect to reproduce the results in future, especially when I scale my system up?

A double batch sparge will extract more sugar from the grain.

what are you using as a mash tun?

Since I am only doing 1 gallon batches, my mash tun is a 6 quart pot, which I lauter the wort using a colander into 12 qt pot for boiling. Then I return the grain back into the mash tun, along with water from my "HLT" for batch sparging.

omokoro said:

Also, is this some sort of anomaly-- can I expect to reproduce the results in future, especially when I scale my system up?

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It's tough to know exactly what to expect when changing multiple variables.

The grain crush can have a big effect on efficiency. Your sparging technique can too.

What did you do with it. Did you add water to bring it down or did you leave it and just have a higher OG.

uncommonsense said:

What did you do with it. Did you add water to bring it down or did you leave it and just have a higher OG.

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Actually, my original reading was 1.090 before I topped it off. I am sure I broke a couple of cardinal rules. I did not end up with my desired volume, so I add some water to the (1 gallon) carboy, shook it up with my sanitized hand on top, then took another reading. The water I added took it down to 1.070. I guess in the future I'll keep some sanitized water on hand. If fermentation stops in the 1.015-1.020 range, I should have a beer with close to ~ 7% abv (est. 5.5% abv), which I don't mind, as long as it tastes balanced.

I just hope I can reproduce these results, since I will be basing my future recipes on 85% efficiency.

I've topped up with green garden hose water and had no issues. YMMV

I've also used a gallon of grocery store distilled water.

I would not expect that level of efficiency in a 5 gallon batch.