2nd AG batch. 1st Efficiency Problem. Thoughts?

[g-star]

So I did my 2nd AG batch today, and my efficiency was significantly lower than my first attempt. (63% vs. 76%).

Both recipes were 90%+ two-row pale with some specialty grains (no adjuncts). I hit my mash temps dead-on (154F) both times. I double batch-sparged with 170F water each time, collecting the same amount of wort into the kettle (6.5 gallons) for both brews. Both boiled for 60min.

Brew #1: Target OG = 1.069, measured OG = 1.067.

Brew #2: Target OG = 1.070, measured OG = 1.061.

I kept my process and equipment identical each time. The only difference is that my first batch was my own recipe with grains crushed at the LHBS. Brew #2 was a (milled) all-grain kit from AHS.

Is it possible that the crush could be that poor on batch #2 that I would take that kind of efficiency hit? I find that hard to believe, but that is really the only variable I can think of.

Any thoughts? Thanks for any valuable insight, as always.

 

[yodalegomaster]

Could it have anything to do with different water ph? If your first kit acid malt it would lower your PH and increase your efficiency? I would get some latic acid and treat your water back down to 5.2 PH. It makes a big difference in the efficiency. I live in the Midwest with very hard water.

 

[g-star]

Good thought, but I forgot to add that I used 5.2 stabilizer for both batches, so I don't think that's it.

 

[dedhedjed]

I've always gotten good (75-80%) efficiency with AHS crush FWIW...no other variables?

 

[g-star]

No other variables that I can think of, which is why I felt compelled to ask you guys about it.

The crush looked OK to me, though I didn't closely inspect it before brewing. I trust the guys at AHS know what they're doing, and that's why I find it so hard to believe its the crush alone causing this kind of drop in efficiency. I just can't think of another good reason...