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-   -   low attenuation (http://www.homebrewtalk.com/f163/low-attenuation-371050/)

mccartney 11-30-2012 06:42 PM

low attenuation
I just want to say im a big fan of the site, ive been reading forums here for about a year. whenever i have a question this is the first place i go. i just decided to finally sign up because i felt i needed some real brewers advice about a current batch. heres the issue

im not sure if this batch has a stuck fermentation. the OG was 1.082 at about 68-70 degrees. the temp has stayed constant and after 8 days i took a reading of 1.039, and 2 days later 1.037. this only gives me about a 54 % attenuation when i am using a wlp090 which should have around 80% att i think.

i added 1lb of dme and 2 lb of table sugar during boiling in addition to the recipe. im wondering if adding the table sugar before letting the malt ferment first was a mistake, but i thought just 2 lb wouldnt make a difference.

also im wondering if since i had such a OG that maybe im being impatient and just need to wait longer for it to ferment. the fermentation hasnt stopped completely but the airlock bubbles are coming out every 30 sec or so. ive tried shaking up the bucket a couple times and it seems to release more c02 for a few seconds then back to normal.

am i being impatient or is there something i can do to get a better attenuation from this?

mgortel 11-30-2012 06:58 PM

That is a higher gravity beer and its only been 10 days.....your only issue is patience....it will be fine. Wait AT LEAST another week before checking it...I would wait 10-11 more days myself.

I primary all my beers (normally) for 3 weeks min.

What temp is the beer fermenting at and what yeast are you using.

RmikeVT 11-30-2012 07:01 PM

Couple questions:
Did you make a starter? 1.080 needs a starter with liquid yeast, or you need to pitch two tubes.

Did you aerate? with a gravity that high you definitely need plenty of o2 for yeast to multiply. I think it is probably too late to aerate again, although Im not sure.

Pitch another tube of wlp090, I would recommend pitching another packet of US-05 or Nottingham, follow the directions on the packet.

Whattawort 11-30-2012 07:03 PM

Did you do make a yeast starter? You've probably stressed those buggers out if you didn't have the proper pitching rate with that OG. Wait a couple of days and get a grav sample. In the mean time go pick up a vial and some dme and make a starter. If you're still not where you want to be, you can pitch the starter. Some might argue with me, but better to have more than not enough. There's a sticky on how to do one.

bobbrews 11-30-2012 07:07 PM

Wrote this in another thread... It may only partially apply if you're not brewing Full Extract.


Originally Posted by bobbrews (Post 4636506)
Easy fix...

Use Extra Light DME that has ppg ratings close to that of real 2-row, e.g. 37 ppg. I would recommend adding about half of it at flameout.

Be extremely accurate with your recipe; weights, volumes, gravity points contributed, evaporation from the boil, etc. (it may simply be a recipe issue). Employ full volume boils with no top off water whenever possible.

Don't add too much crystal. Keep it below 7% total.

Do substitute 10-13% corn sugar at flameout in place of extract. You'll need about double what is typically seen in all grain recipes. This technique works very well but is better in pale, low to moderate bodied American ales.

Make an appropriate sized yeast starter with high attenuating yeast. Intermittent shaking is good. Stir Starters are better. Yeast nutrient and/or amalyze enzyme may help.

Aerate the wort well before pitching the yeast.

Keep your temperature control down pat for the duration of the yeast starter & primary. For instance, with Cali Ale yeast, consistent ambient air temps in the low 60s should work very well for you (if you don't have a thermometer to measure the wort/beer more accurately).

If all else fails, look into partial mash with some real 2-row in place of extract. Mash the grain around 147 F for an hour.

And lastly, patience. Give your beer 3-4 weeks before bottling.

mccartney 11-30-2012 07:08 PM

thanks for the quick reply. i took a temp this morning of 70, and the yeast is wlp090 san diego. i just got worried because the bubbling has slowed down a lot. i thought it was pretty much done.
do you think after 3 weeks ill be looking at an att of atleast 75?
what about a secondary fermentation. should i leave in in the primary for those 3 weeks or would secondary carboy be an option? id like to free up the bucket for my next batch as it is my only bucket, but not at the cost of ruining this batch.
also i only have 1-1/2 oz bittering hops and 4 1/2 oz of aroma. would this high gravity benefit from a dry hopping? if so at what point?


i didnt make a starter, i just pitched it right in as soon as the temp was right. and yes i not only aerated, i oxygenated it with a diffusing stone for about 30 sec

mgortel 11-30-2012 09:38 PM

I wouldn't take it off the yeast cake and put in secondary.....go ahead and at least pitch another yeast pack....but do not aerate....just dump it in.

The other guys bring up an excellent point I didnt even think about (i must have assumed you did starter even though u didnt mention it) ...you should have done starter from beginning....but I think now if you just pitch another pack/tube you will be ok.

Also, when using liquid yeast.....you should always do a starter even for "normal" OG beers....have you ever done a starter? If not it is easy.....plenty of info on this forum just do a search.

WoodlandBrew 11-30-2012 09:59 PM

Based on the three reading you have taken my bet is that it finishes on 12/4 with a FG of 1.034. I'm afraid it is looking like your final attenuation will be 58%.

But this is really just a guess based on an exponential fit of the data. It hasn't failed me thus far, but I hope this is the first time.
(like this: http://woodlandbrew.blogspot.com/201...tion-time.html)

If your readings were off by one each and the right direction then it could be 1.027 on 12/13

LME or a high mash temp would explain the problem.

Just in case it is stuck:

Top ten causes of a stuck fermentation:

Top ten ways to fix a stuck fermentation:
Only time will tell.

mccartney 11-30-2012 11:07 PM

thanks for all of the responses.
so pitching a dry yeast pack will increase attenuation?
i know my readings were correct because i used a refractometer and calibrated before each use. and yes i used lme for the base malt, i havent yet graduated to all grain.
next time i will for sure make a starter, probably for every batch is a good idea. if i wait until the fermentation slows down next time before i add table sugar would it still stress the yeast? or is it just the initial high gravity that stressed them? if i add sugar later in the process should i also add a package of yeast along with it?

my next batch when i free up this bucket is a belgial trippel, a high gravity brew to start with. will a tube of wlp090 with a starter be enough for that? what about if i decided to add sugar to it?

you guys are awesome, i aspire to be like you :)

WoodlandBrew 11-30-2012 11:30 PM

Did you compensate for alcohol when using the refractomerer? That would explain it.
Try a hyrometer just to make sure.

You are probably at 1.008, and it will finish at 1.005 on 12/4

Here is a calculator: http://www.northernbrewer.com/refractometer-calculator/

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