My first several AG batches were running somewhere around 85% efficiency. Today I did a brew using 10 lbs of pilsner malt and got 6 US gal (23L) of 1.042 wort. I calculate that to be around 70%. I guess that's ok but I can't figure out why it's gone down so much. I am using 2 quarts per lb of grain, mashing at 150, using 50% distilled water and 50% tap to reduce my carbonates and hardness. Mash was 5.4 pH after adjustment with citric acid (nothing new). Just can't figure out why I've dropped 15% or so and it's bugging me.