Check Your Thermometers

Not too long ago I brewed a beer, pitched my yeast, and thought all was going well. Then about eight days later I discovered fermentation had stopped well above where it should have (63 percent apparent attenuation versus the 78-81 I had been seeing with the same yeast).

I went and checked the thermometer I used to mash in and found it was reading five degrees higher than another one I had. I won't presume the second thermometer to be dead-on, but it does read exactly the same as my house thermostat, so I think it's in the neighborhood.

So what does this mean? I probably mashed closer to 160 degrees as opposed to the 155 I was aiming for. (And I only went that high because I thought the thermometer was actually reading high... HA!)

Moral of the story: check your thermometers. Don't take anything for granted. And if you suspect that a thermometer has been acting up on you and can't be trusted... you're probably right.