90% efficiency WTF?

[bwarbiany]

So, this is only my third batch on the new rig. Previous efficiencies were 81% for a 1.055 beer and 77% for a 1.065 beer, pretty well in line with what I've seen previously. Generally I've seen around the 80-81% for beers under 1.050, and dropping off a bit as the beers get bigger.

So last night I brewed a Patersbier, target OG of 1.046. I ended up with 1.052. By my reckoning, that's 90% efficiency, which I've never seen before on either my old rig or my new one.

I changed nothing in the crush, so that's not it. One thing I did this batch was to add some gypsum to the mash, and to acidify it with a tsp of lactic acid in the mash, and 2 tsp in the HLT. Deliberate acidification is something I've never done before.

Obviously, a portion of this could be volume-related, as I doubt my volumes are exact. But 90% is still higher than I've ever seen, or even gotten close to. And it wasn't just boil-off, as my preboil gravity was 1.043 when 1.037 was expected. I used Brent's spreadsheet for volume measurement as it was using his old kettle, so I think the preboil volume measurement was close enough that it doesn't explain this big of a difference.

Could acidification have given me that big of an efficiency bump?

[brahn]

I don't believe acidification should have any impact on extraction unless your pH was way too high before. I haven't noticed any change in efficiency at all between batches where I corrected for pH and haven't.

It's totally normal to get higher efficiency with a lower OG, and combined with some questions about the volumes I'd lean towards that being the culprit.