Consistently Over Shooting FG

I've run into this problem for the last several months and I never used to have it before. I am DRAMATICALLY blowing through my estimated FG numbers. This didn't used to happen. I was always within a point or two of my Beersmith FG target. The only recent two changes I have made are a new mash tun and a new thermometer. I made both of these changes with hopes that I would get back on target, but two batches later and it's still the same.

I calibrated the new thermometer in ice water and then boiling water. It was within a degree in each instance. My latest 153 degree mash yielded a 1.050 wort and a pack of Nottingham took it to 1.004! I am consistently hitting in the 1.008-1.005 range regardless of initial gravity.

How well are you holding that temperature throughout the mash?

For instance, a mash held at 153* over an hour will be less fermentable then say, a mash started at 153* that cooled to 148* over the course of said hour. My mash says within 0.1* over an hour.

Also, Notty is a highly attenuative strain. Perhaps try a lower attentuating yeast strain? Have you had this result with other yeasts?

Maybe you should just mash at a higher temp to compensate.

I haven't checked final mash temps. I'm using the standard 10 gal Igloo water cooler. As for yeast, I've used both Nottingham and Safale-05. Have same issues with both. I even went so far as to check my hydrometer in water today to see if it was off.....


Would shorter mash help? I've always mashed for 60-90 mins. Perhaps a 30min mash @ 154 would help?

Just to make sure that I read your post correctly... You were having these issues before you bought the new equipment? So nothing changed prior to it starting?

Have you changed out your hydrometer? The paper inside can move.

If that's not it, I'd suspect a bug in my brewery. I know a lot of people are hesitant to jump to that conclusion, but there's not too many things that can cause this. I'd change out all of my plastic.

Yes, I was having these issues before. I purposely changed out my mash tun and thermometer to see if that would help. In two brews, it hasn't. I checked my hydrometer today in water and it read 1.000. It's beyond frustrating.

Understand... I'd replace all of my cold side plastic. It's something you should do periodically anyway. Bacteria and wild yeast can drop fg past what's predicted.

nobody asked, so I will--how does the beer taste, compared with how you think it should taste?

I only ask because I postd a thread complaining about beer that was....maybe drier?....than I thought it should be. watery, dry, etc.

The beers taste great. They just have little to no body.


I got a brew coming up and a glass carbouy vacant. I'll try that and see what happens.

Cutting down the length of the mash should help. 60 min is usually plenty.

I'm having the opposite problem and I think it's yeast health. I'm repitching but sometimes it's been weeks or months since I harvested and I'm not making a starter. Just harvesting all of the yeast from a 5g batch into quart-sized mason jar, some trub too, and then warming and pitching it weeks later into another batch.

How are you measuring your SGs?
I had hydrometer going from reading 1.02 to 0.94 in a water.
I guess scale shifted. If you OG is coming from a refractometer it could be one of the explanations