[beersabound]

I brewed a Kolsch three weeks ago. Mash temp was 148F. I used WLP 029 and made a starter.  Ferm temp has been between 58-62.  After one week, it was at 1.014.  Now it sits at 1.013.  I'd like it to drop to 1.008 - 1.010. 

Any ideas on how to get it to drop a little more? Raise the temp? Pitch more yeast? Wait it out?

Thanks, Tim

[tygo]

What was your grist?  OG?

[Mark G]

You can try raising the temp into the mid 60s and gently swirl the fermentor. You might get a couple more points out of it, but odds are, after three weeks, it's just done. How does it taste? What was your recipe?

[Jimmy K]

What Mark said.

[beersabound]

OG was 1.047

Grist was 90% Pils and 10% wheat malt.

It tastes okay but it is a touch sweet.

Thanks for the replies.  I think I'll raise the temp on it.

[nateo]

I don't think you'll hurt it going up to room temp with it, though @ 1.013 there's a good chance it's done.

[Jimmy K]

OG was 1.047

1.047 - 1.013 is 73% attenuation - within, though at the low end, of the range for that yeast.  White Labs does say WLP029 "does not ferment well below 62" so that may not have helped. If you warm it to the high 60's and stir the yeast up it may help - if not it may be the recipe/mash and not the yeast.

[tygo]

I think you're probably done.  Last one I did with this yeast went from 1.049 - 1.011.  I just brewed up a kolsch with this yeast again today so we'll see how this one does but I'm expecting similar results.  I ferment at 58F.

Warming it up and rousing it won't hurt, but I'm going to guess you're not going to get much more out of it.

You said you made a starter...how big?

[newrocset]

I have continuous problems with attenuation and I'm looking at starter sizes and mash temps to resolve it.  How big was your starter?  In my opinion a Kolsch needs to be fermented at a very low ale temp, that being said, you need at least a 1 gallon starter for the yeast to eat all those sugars and with a 90% pils malt in your bill, you are likely going to get a load of fermentable sugars rather than a bunch of non-fermentable dextrins - so I'm guessing, even though you made a starter, it wasn't big enough - did you use a stir plate? did you check manufacture date of your yeast?  I had the exact same problem as you w/the Kolsch I did a few months ago.

Here's a case I had with my last batch:
Brewed a 10gal Brown Porter OG 1.060
5 gallons on top of a carboy of ESB yeast from which I just racked off a standard ordinary bitter: it started fermenting the minute the wort hit the yeast, and took one week to make a nice dry 1.008 (I think, though could've been lower) - anyway it fermented all the fermentable sugars and left some pleasant sweet dextrins.
Other 5 gallons on a 1/2 gallon starter of London Ale Yeast (the stuff that's supposed to ferment out pretty well): ended in 3 weeks w/a 1.020 FG....tasty, and actually closer to a brown porter, but too sweet for me.

Moral of the story: I pitched my wort on a giant active yeast cake and it fermented fully, whereas the 1/2 gallon starter just didn't cut the muster....

[beersabound]

I used mr. malty for a hybrid.  It was a 5.5 liter starter with two vials and the vials were less than a week old.

I figure it is done but was hoping it would be drier.  No biggie.  Just something to focus on for the next batch.

[tygo]

Well, that should have been plenty of yeast then.

Are you sure about your mash temp?  You have a good thermometer?

How did you aerate the wort?

[nateo]

I have continuous problems with attenuation and I'm looking at starter sizes and mash temps to resolve it. 

There are two philosophies for yeast performance. Beer guys only really care about mash temp and yeast count. Wine guys care a lot more about the yeast's needs throughout fermentation, and pitch at much lower rates for much higher gravity than you'd want for brewing. Wort and must aren't the same, but it's something to think about.

I try to rouse my yeast every day until I hit terminal gravity. It keep the yeast in suspension and blows off CO2. CO2 in solution = carbonic acid. During fermentation, when lots of CO2 is being produced, the pH can drop low enough to inhibit the yeast. If you pitch enough yeast, it can plow through anyway. This effect is exaggerated in mead and wine fermentations, but I've noticed similar effects when fermenting wort.

[udubdawg]

FWIW, made my first Kolsch last year.  148F, WLP 029, 1.047, just like yours.
also finished at 1.013.  I carbed it a bit higher than usual to lighten it up.  It won three silver medals, always beaten by another style.
subsequent tweaked batches have no trouble getting to 1.008, but I think I still prefer that first one. 
I also feel this yeast performs great at higher temps like 65-67.  Love that slight white wine grape fruitiness with just a hint of tartness.

cheers--
--Michael

[beersabound]

Well, that should have been plenty of yeast then.

Are you sure about your mash temp?  You have a good thermometer?

How did you aerate the wort?

I am pretty sure about the mash temp.  I calibrate the thermometer before each brew.  Any recommendations on a bullet proof, accurate thermometer?

I aerate with pure O2 and one of those stainless 2.0 micron thingies. 

I use the same O2 procedure and thermometer for all brews and usually get pretty close for expected terminal gravities.  I am guessing it has to do with ferm temp.  But, first hybrid for me and I don't make lagers so it's a new adventure of sorts.

[tygo]

I am pretty sure about the mash temp.  I calibrate the thermometer before each brew.  Any recommendations on a bullet proof, accurate thermometer?

I like this one:  http://www.thermoworks.com/products/thermapen/

It's pricey but it's durable, accurate, and reliable.