Sudden, consistent efficency drop

[Docjowles]

So on my last four batches, I abruptly went from getting 75% efficiency (exactly where I want it) to 55-58% every batch which I consider unacceptably low. Been racking my brain but I don't think anything in my process has changed. I have my own pet theory but I wanted to ask for any other thoughts

Relevant info:

• I mash in a 10 gallon circular cooler with a stainless false bottom and ball valve.
• I usually drain the mash tun, then batch sparge in 2 equal batches. Sparge water is 185 and the grain bed ends up around 165. For moderate gravity beers, each batch ends up being about 1/2 the volume of the strike water for the mash.
• I crush my own grain using the LHBS' mill.
• My mash temps aren't nutty, even if I miss by a couple degrees (148-156).
• I give the mash at least an hour and sometimes up to 90 minutes to convert
• I've had this problem both when I end up with a little extra liquid in the MLT and when I hit my volumes 100% perfect.
• I am very confident in my volume measurements (measure water in with a 1 gallon spring water jug, measure volume in the kettle with a calibrated stick accurate to 1/2 gallon)
• I do my best to stir the crap out of the mash and every sparge batch with a metal spoon
• I get this problem on all sorts of recipes. It has so far affected an American brown, an American IPA, a dubbel, a saison and a wit (which I'm not totally counting since it was 50% raw wheat and oats)

None of that has changed since I was getting good efficiency numbers. My own list of possible problems:

• My LHBS reorganized their entire shop, and my first batch after that happened was when my efficiency took a dump. I think maybe the grain mill got bumped wider, by accident or on purpose. This is my leading conspiracy theory :cross:
• My mash pH tends to be too low according to my ****ty color strips. Like, below 5. But it also says my tap water is in the mid 5's which seems ludicrous for city water, so I am not sure I believe them. Any water experts reading?
• My spoon can't always reach the bottom of the mash without burning the crap out of my hand. So it's possible I am getting dough balls. But again, I used this spoon when I got 75% so I doubt it. I plan to buy a paddle or big whisk or something soon.
• My thermometer has suddenly gone out of whack and I am trying to mash at 165 or something goofy

So there you have it. My prime suspect is poor crush at the LHBS but I am open to anything. Thanks for any other ideas.

 

[MalFet]

With any efficiency problem, your first step should be to figure out if you are losing your sugars due to poor conversion or due to poor lautering. The article on Braukaiser.com called "troubleshooting brewhouse efficiency" can help you do this.

Poor crush sounds like as good a candidate as any, but anything we could say will just be idle speculation without some numbers to help us understand what is happening.

 

[Docjowles]

Thanks! I will absolutely go through that article and report back.

 

[wilserbrewer]

Poor crush can likely be identified by taking a handful of crushed grain and taking a close look at it. Any whole or uncrushed grain where the interior is not easily exposed to the mash should set off the alarms of concern.

 

[charless]

Calibrate the thermometer. Buy PH strips with the 4 colors on the strip or get a PH meter. I'm guessing it's the thermometer. it may read low.

Go Sox,
cds

 

[Northcalais40]

Address your issues. Stirring is very important. Get a paddle. If you know a woodworker, give them beer, they'll make you a paddle in 10 minutes. Get a second thermometer, for $12. Check the crush for sure. Don't sweat the water, it always works.