very high attenuation with US05

[goschman]

Hi All. This is my first time posting here. I was wondering if anyone else is experiencing really high attenuation when using US05.

Over the last 10 batches that I have brewed, I have been experiencing an average of 86.8% apparent attenuation with some over 90%. All batches with the exception of one have finished at or below 1.007.

*as far as I can tell my thermometer is calibrated
*mash temps are between 152 - 154
*same recipes are experiencing consistent fermentation results
*similar results regarless of new packet of US05 or harvested yeast slurry

I used to get about 78% avg attenuation using US05 at my house before moving operations to my buddy's house. The only change has been where we get our water. Could any differences in water make this significant of a difference? Any thoughts?

[dannyjed]

I get anywhere around 78-82% attenuation when I use US05.  I think that the water could definitely make a difference and I'm sure some others will chime in that are more experts in water than myself.  What about aeration of your wort, have you changed anything with this?

[bluesman]

How does the beer taste? What's the mouthfeel like? Have you tried calibrating your hydrometer?

[goschman]

The mouthfeel is dry but most of the beers have turned out pretty good in my opinion. The biggest problem we are having is getting too high of an ABV%. Most of our beers have been ending up a full 1% above where we would like them. I just started accounting for the high attenuation in newer recipes so that the results are more accurate and we know what to expect. I figure we have two options if we can't find what the cause is; 1.) switch yeast or 2.) use less grain (thought the FG will still end up very low)

Honestly, I have never thought about the hydrometer. We have two so I will compare their readings next time we brew.

We will be upgrading systems in the upcoming months so I don't want to mess with too much now since a lot will be changing.

It appears that either the hydrometer or the change in water may be the culprit.

[anthony]

I saw a thread on tastybrew where you also posted this same issue. I think your best option is to a) get another thermometer as backup and b) keep increasing your mash temperature until you get an attenuation you want.

80% attenuation with US-05 with a mash in the low 150s or high 140s isn't uncommon. If you want to keep using dry yeast, then recipe modifications might be in order, but the modification wouldn't be less grain. The thing you would want to do is sub out some base malt for something less fermentable and with more dextrins. One easy way to do this is blend some of your base malt with one of the many "Mild" malts available.

If you truly want to find the cause, then you need the manipulate just one of these variables until you fix the issue. I would probably choose the mash temperature (with new thermometer).

[denny]

If you truly want to find the cause, then you need the manipulate just one of these variables until you fix the issue. I would probably choose the mash temperature (with new thermometer).

This sounds like a sensible course of action.

[goschman]

Thanks for the advice. I have been adding more and more crystal to some recipes to see if that would change anything. I guess the first step is to get a thermometer and work on the mash temp