always have low attenuation, what's up?

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hexXedBrewing

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So I've made 9 batches so far, and just had my first all grain batch. For whatever reason, I'm getting low attenuation rates like around 65% to 70%. all using 2liter starters and white labs. I've even tried super San Diego yeast and I only got 71%. I've gotten 76% twice but they were both low gravity beers. can anyone lendme some hints? my temperatures for all my beers are about 69F.
 
In addition to mash temps (as RKB82 asked above), your recipe will also affect attenuation. Crystal/caramel malts, for example, add unfermentables to the wort that the yeast won't eat up. In other words, they raise your FG, lowering your attentuation percentage.

Where is your FG ending up? What you are really interested in is hitting your target FG, not the attenuation, which is just a percentage. For example, my Belgian Golden Strong had a huge attenuation, because it started high and ended dry (as intended). My cream ale ended dry, also, as I wanted it, but the attentuation is lower because it starts lower.

To increase your attenuation or to get a drier beer on, say, a basic APA, try following these steps:

1) pitch using either rehydrated US-O5 or make a big starter of WLP001
2) use no more than 1/2 lb total of crystal or caramel malts in a five gallon batch
3) mash at 148F - 150F for 75 minutes
4) oxygenate your wort - pouring into your bucket back and forth, stirring the wort in the bucket vigorously, shaking the carboy, or adding pure O2 through a wand
5) start your fermentation at 62F-64F and when the active fermentation slows, raise it to 68F - 70F.

Hope this helps!
 
your post is vague and this is a complex issue.


Possible problems..

mash temp too high
too much crystal/cara malts
too little healthy yeast
too low of a fermentation temperature
not enough wort oxygenation
strain of yeast
 
Opps I did not read his original post correctly.

I assumed that he was an extract brewer.
 
yea I know it's vagueI'm really sorry. It's just that it's been such a long running issue.

So here's my last batch:
All grain
15lb of pale malt
1lb of crystal 60
1lb of carafa II
149F perfect mash temp for 60mins in my cooler.
did first runnings and then another test at 149F for 40 mins for my second runnings.

90 minute boil. with 15 minute wort chill to 75F.

OG came out to 1.081 at 5.0 gallons. 67% mash efficiency. =(

San deigo super yeast white labs 2 liter starter. on a slow stir plate.

I always pour the wort at 75F to my primary bucket through a sanitized strainer to catch the moss and hops, and for extra aeration.

Fermented first two days at 72F and then a total of 15 days at 68F.

I took the FG while racking to secondary and it's 1.025. I'm holding secondary at 60F for 3 days with dry hops, and then I will bring it down to 35F and hold that for 10 days.

That's pretty much all I did.

Should I really be pouring the wort back and forth, I would be afraid of contamination.
 
I'm not sure about the pouring back and forth, I don't do that. But for a 1.081 beer, getting enough oxygen for the yeast is an issue. Pouring through the strainer may be enough.

That's a big beer, so that will affect attenuation, too - as the fermentation continues, the environment will get more hostile for yeast (because of the alcohol) as they keep trying to do their jobs.

Lowering the fermentation temps as you go is counter-intuitive to me. As things are getting harder for the yeast, you make it even harder by chilling them. Plus, the off-flavors associated with higher fermentation temps mainly develop early in the fermentation.

The crystal 60 is going to add sugars that won't ferment. I've not used Carafa II, so don't know if that is true for it, also.

Before giving up in despair ;) maybe try a nice, regular sized APA or brown ale, something around 1.050, keep the crystal at a minimum, reverse your temperature regime, try a US-05 (known for super attenuation and according to some doesn't require oxygenation) and see how it goes.

I can hear your frustration. Let us know how things go for you.

Edit: Have you double checked your thermometer for accuracy, that you are accurately measuring mash temps?
 
Edit: Have you double checked your thermometer for accuracy, that you are accurately measuring mash temps?

This...

and also, Yeast do not like to be cooled, they do like to be warmed.


You always want to start the fermentation lower and then raise, the converse is not adviseable. This may be your problem, although 72-68 is not a huge difference.



My advice is to check thermometer accuracy

Brew a smaller beer Og1045-1065

Spend more time shaking the carboy, or invest in an oxygenation system

Finally ferment your beer cooler to start and then raise it.

Realize that the White labs and wyeast fermentation temperature ranges are not specifically relevant to homebrewers because of the scale of our operation. For instance I ferment WLP001 in the high 50's to low 60's for the start and let the temperature come up naturally(driven by yeast activity) through the fermentation proccess. In the summer I will have to activily cool in it the first few days because it will rise too quickly.


The important thing is to make sure you get into the 68-70 range towards the end of active fermentation and especially afterwards for a bit to let them consume and diacetyl they have produced and finish chewing down those last remaining consumeable sugars.
 
I can definitely see that warming up the yeast makes more sense from 68F start to 72F after a few days.

I've always read to start the pitch around 75F and let it come down.

Thanks for the advice!
 
Just to be clear, I would not propose fermenting anything(other than a belgian or saison yeast) at that high of a temperature. In general the mid 60's are your friend and even lower is better for some.
 

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