over attenuation problem

I've been having a recurring problem with my beer overattenuating. I routinely get over 80%, as high as 85%. The resulting beer is usually watery with not much flavor going on. The hoppy beers are basically hop water, and the more malty styles are not very malty at all. I brewed a scottish ale with a pretty malt heavy grain bill (munich, crystal, etc) and the apparent attenuation was 82%. It turned out really plain with a little bitterness. Not really off flavors really, just a lack of maltiness.

I brew all grain and mash in a cooler and batch sparge usually getting 70% efficiency. I control my fermentation temps, usually fermenting cool around 65F. I pitch from a 1 liter starter and aerate by shaking the carboy. So I thought my yeast practices were pretty good, but I can't figure out why it over attenuating. I guess the tasty residual sugars are getting eaten up. I thought wild yeast, but wouldn't that cause a funky flavor?

Oh yea, this only happens with my all-grain beers. Extract batches have been fine.

Any ideas?
thanks

Aron

What temp are you mashing at? Sounds like you are mashing low.

Mash at a higher temperature. I used to have this problem as well, and the reason was that my mash thermometer was off. I was routinely mashing for 60 minutes @ 148F...and therefore all of my beers were finishing at 1.010. I can't say that they tasted watery, but they were all very dry. Once I figured out the problem, I replaced the bad thermometer and was hitting the proper mash temps, usually in the 152-154F range. What temp do you usually mash at?

well, i've mashed as low as 149 and as high as 156. Both have similar attenuation. I bought a new thermometer but I'm not too sure how to calibrate it. I just compare all 3 of my thermometers and if they're within a degree from each other, I assume its ok.

what about grain crush? I grind pretty fine.
Is grain/water ratio an issue? I go with 1.3 qt/lb

I don't brew AG so I can't comment on that, but you could try a lower attenuating yeast strain.

dub_A said:

well, i've mashed as low as 149 and as high as 156. Both have similar attenuation. I bought a new thermometer but I'm not too sure how to calibrate it. I just compare all 3 of my thermometers and if they're within a degree from each other, I assume its ok.

what about grain crush? I grind pretty fine.
Is grain/water ratio an issue? I go with 1.3 qt/lb

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Well, I typically use 1.25 qts/lb for all of my brews so that ratio seems fine. Just out of curiosity, what OG/FG have your beers been and what recipes were used?

my last batch was Jamil's Alt recipe from his new book. The OG was 1.056 and the FG was 1.010. That's 82% right? I mashed at 149F and fermented with Wyeast German Ale yeast at 60F.

Another one I can recall is DC's Rye IPA. The OG was 1.072 and finished at 1.011 (85%). Fermented with Wyeast 1056 at around 68F. That one came out really thin and overly bitter and I know that recipe is a proven winner.

thanks for the help
Aron

If you are only experiencing this when you do AG then it pretty much has to be your mashing technique.

I would get a new thermometer and make sure it reads 32 when put into a glass of ice with a touch of water and 212 when put into boiling water. I had three, yes three analog thermometer, that were all off. Two were very close together but still a few degrees high. This was causing me to mash too low and get very dry beer also. I am now using this thermometer: https://www.amazon.com/gp/css/summary/edit.html?ie=UTF8&orderID=002-0748949-6745052 I am very happy with it, was accurate out of the box and gives an accurate temp very quickly.