Attenuation Problem

Since i've switched to AG over a year ago, i haven't had any problems with attenuation. The one thing i've changed is using a theif to take my gravity readings. i'm using the same hydrometer i've used for years. my fermenting temps are around 68-70 (like to stay away from 70 but this time of year it gets a little warmer).

My IPA finished around 1.021 when target was 1.015, now it doesnt taste all that sweet, but with the hops, it might cover that up some. i made a stater of liquid California ale yeast per mrmalty.com, and i've brewed it before and had it finish correctly.

my blonde ale finished around 1.025 and that was using two rehydrated US-05 packets, this beers OG is around 1.050.

anyway, i'm stumped a little on this. maybe my thermometer i use for mashing is off, and i'm mashing to high? i've been using it for at least a year though.

Hey Evan, I brew in Charlottesville as well and would be interested in taking a look at the water profile--this could be affecting our attenuation. I have an oktoberfest lagering and a dunkelweizen fermenting, I am curious to know if our water has anything to do with it as I have not done any tests on it. You could easily see how off your thermometer is by sticking it in boiling water and seeing if it reads 212, thats what I do.

i haven't looked into my water, but i didnt run into this the same time last year. but i hadn't thought water could be the problem. i was planning on checking my thermometer tonight. its the only thing i can think of (maybe water now?) that could be throwing me off.

shot0rum247 said:

Hey Evan, I brew in Charlottesville as well and would be interested in taking a look at the water profile--this could be affecting our attenuation. I have an oktoberfest lagering and a dunkelweizen fermenting, I am curious to know if our water has anything to do with it as I have not done any tests on it. You could easily see how off your thermometer is by sticking it in boiling water and seeing if it reads 212, thats what I do.

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That's the wrong Evan. I don't think he's in Charlottesville. Here's our water profile (at least, the profile for the area served by the South Rivanna Water Treatment Plant:

Ca: 16 ppm
Mg: 9.7 ppm
Na: 5.1 ppm
SO4: 18.4 ppm
Cl: 5.6 ppm
HCO3: 14.9 ppm

I don't think it has anything to do with attenuation though. Some of my batches to get stuck around 1.020, but when I pitch that stuck batch onto a big ol' yeast cake, it always finishes it out, without fail.

Evan said:

i haven't looked into my water, but i didnt run into this the same time last year. but i hadn't thought water could be the problem. i was planning on checking my thermometer tonight. its the only thing i can think of (maybe water now?) that could be throwing me off.

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How do you oxygenate your wort?

Evan! said:

How do you oxygenate your wort?

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Shake the carboy method. Not the best I know, but it worked before these last two batches.

Hm. Try a stone and an oxygen tank. Might help. I know it "worked" before, but if you haven't changed anything, then I don't know what else to tell you. The two things, in my experience, that affect attenuation are oxygenation and yeast viability/count.

Also, if you do get stuck, my foolproof method for finishing it out is to pitch it onto another active cake.

hahaha Evan!....you are the man...how silly of me. Thanks for the c-ville water profile too!

I'd say double-check your mash temps/thermometer. I shake-aerate and typically get within the yeast's attenuation range stated by the manufacturer. Heck, I even recently got ~68% attenuation with Windsor yeast, which I thought was pretty good, with just shake-aerating. For all the times I've had poor attenuation, I can attribute it to mashing troubles where the temp got too high for one reason or another.

I usually get ~80% with US-05 and Notty....

my aeration method is to dump the wort (after it's cooled) from one ale pail to another 2-3 times.

I've got three dial-type thermometers and they do not stay calibrated. Have to check once a year and adjust them.

david_42 said:

I've got three dial-type thermometers and they do not stay calibrated. Have to check once a year and adjust them.

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that's the type i have, i will check after dinner tonight.

Thanks everyone for the help!

Although this is a bit of a pain--when i transfer cooled wort from my brew kettle to my fermentor i do not use any sort of tubing but rather have a brewing associate hold my funnel w/ screen as I pour through it. It takes a sanitized spoon to move some of the hopp/grain matter off the screen every once in a while but this aerate the wort really well as it falls into my primary from about a foot above...I used a dry yeast just the other day (LBHS was out of the liquid i really needed) and got bubbling within 75 min.