So I've recently had to start brewing without any helpers. My efficiency has dropped from 75% to a consistent 57.5%. WAT?!! Seriously three batches in a row at exactly 57.5%. Luckily except for the first one I adjusted the recipe accordingly and nailed the OG anyway. Except that first one, the doppelbock recipe turned itself into more of a bock.
I have no idea why going solo would do this. I'll explain below my process that I used last night. Recipe - 13.5# 2-row, 3.5# flaked corn, 6 oz white wheat, 5 oz amarillo at various times. 7.5 collected and 5.25 into bucket (all exactly as expected, except .25 gallon low into bucket. Phone turned off mysteriously and lost my boil timer.) OG 1.071, yeast belle saison pitched without rehydrating.
Anyway on to the process. 12 gallon coleman cooler with a kinda beat up stainless steel braid for lautering. Heat up mash water, add grain, stir, mash in at 148F with 6 gallons water. 20 minutes later, add 1 gallon boiling water to bring up to 157F until sparge water heated (15 minutes or so.) Stir again. Vorlauf, drain into kettle lined with grain bag. Add 175F 2.75 gal sparge water, stir, wait 5-10 minutes, drain (standard batch sparge.) No vorlauf on the sparge, I had everything including the pitcher full of wort already so just filtered with the grain bag. I boil in 2 kettles so I tried to take an average of the 2 kettles to get the boil gravity which I calculated at 1.056 which was obviously off since I ended up at 1.071 @ 5.25 gallons. Didn't think refractometers needed temp correction. 90-ish minute boil.
There's of course some dead space and some water left over in the grain, but it should be pretty weak wort left behind right? Is there something intrinsically wrong with the way I'm sparging, should I break it up into multiple steps?
I don't know if anybody can see anything wrong in this description, but I figured since I can't figure it out I might as well ask here.