A pattern has emerged on my last few brew days: mash+lauter efficiency has dropped. So I decided to do some basic troubleshooting. Have I changed any procedures? No. Equipment? Yes. I purchased some “precision” hydrometers and have used them on my last three batches.
So I decided to test my old and new hydrometers. It turns out that the triple scale hydrometer
I have been using all along was off by four points. Here’s the surprising thing: ALL THREE of my triple hydrometers are off by exactly 4 points! My new precision hydrometers are dead on.
Shame on me! I tested my hydrometer when I first started brewing, and I remember it being off. I didn’t care though. I figured as long as I use the same hydrometer to test OG and FG, the outcome would be the same whether or not I compensated for hydrometer being off. I still think that’s sound logic, but only for extract brewing. That logic does not hold in all-grain brewing when you are taking gravity readings to check your mash efficiency. I knew better. I was just being lazy.