Higher than expected efficiency?

First, let me start out by admitting I haven’t gotten a water report yet–It’s on my to-do list, though!

Over the past 10 all-grain batches, I was getting a very consistent 72% efficiency and getting very close to my target gravities. Grinding with a corona-style mill, mash in a cooler with false bottom and batch sparge, and with a mesh bag and a dunk sparge. Regardless of the specific technique, the end result was very consistent.

However, on my last two batches, a porter and stout, I seriously overshot my target gravity, and to hit the numbers in Beersmith I had to up the efficiency to 87% and 82%, respectively. These two specific recipes called for calcium chloride, and it was the first time I used it with my well water.

I’m a rookie at water chemistry, but is it possible that a 5-gram addition of calcium chloride could end up with that big of an efficiency bump given a certain unknown water chemistry? I can’t think of any other differences from brew day.

If anyone has any other ideas I should consider, I’m all ears. My goal is consistency, not super-high efficiency, so whatever I can do to make the end result match the recipe would be great.

Is that mash efficiency or total brewhouse efficiency?

Mash efficiency, I believe.

It’s possible the added calcium chloride lowered your pH to a level where you would get better efficiency but I don’t know enough about the chemistry side of things to know if you could experience a 15% increase. My gut tells me no but that’s just a guess.

Is it possible you improved flow or eliminated dead space in your mashtun?

I agree - that big of an increase struck me as odd, but I can’t think of any other differences. If it could have made that big of a difference, I would have thought my previous brews would have suffered from significant issues with tannins or other off flavors.

With mashing in a bag in a cooler, I literally have no dead space, and the only loss I have is from absorption. It’s a pretty awesome way to mash (thanks Dave!), and I would chalk it up to that, but the porter at 87% was done in my mash tun with false bottom/batch sparge. The stout was at 82% and done with the bag in the cooler.

I must be missing something. Not complaining about the improved efficiency, but without knowing how to account for it I don’t want to switch all my recipes over and end up missing on the low side.

Off the top of my head the only things I can think of that would cause such a big boost in efficiency would be either a much better crush or an error in measurement of something (e.g. grain weight, volume of runnings, gravity of wort).

Thanks Matt, my head is in the same place, which is why it’s bothering me. It’s hard to plan a recipe when you’re getting anywhere from 70-85% efficiency.

I’m sure the fineness of the crush with a corona-style mill is all over the place, so the simplest explanation is that the crush was probably a little (or a lot) finer than previous runs. I’ll just have to try a few more batches and see if it falls into a new pattern.