# Yeast Attenuation % Very Low



## jamiefbacon (28/8/11)

Hi all
Ive brewed about 6 biab beers and every one im having trouble hitting my target FG level im using a ferment fridge so temps are at 18 degrees for the whole ferment and every time ive been using 1 packet of craft brewers own version of us05 yeast. My last beer a 10min ipa og was 1062 with a target fg of 1015 and it only got to 1.024 any ideas why this is happening not enough yeast at the start maybe imm not sure??

thanks


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## bigandhairy (28/8/11)

jbacon said:


> Hi all
> Ive brewed about 6 biab beers and every one im having trouble hitting my target FG level im using a ferment fridge so temps are at 18 degrees for the whole ferment and every time ive been using 1 packet of craft brewers own version of us05 yeast. My last beer a 10min ipa og was 1062 with a target fg of 1015 and it only got to 1.024 any ideas why this is happening not enough yeast at the start maybe imm not sure??
> 
> thanks


Hi jbacon,

what is your mash temp? also have you calibrated your temp probe and your hydrometer? my probe is out by half a degree and my hydro is out 4 points. no biggie, I just take it into consideration when taking readings, but if I was unaware it would cause my problems that I didnt really have, ie fg readings that are 'higher' than they are supposed to be etc etc

bah


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## jamiefbacon (28/8/11)

bigandhairy said:


> Hi jbacon,
> 
> what is your mash temp? also have you calibrated your temp probe and your hydrometer? my probe is out by half a degree and my hydro is out 4 points. no biggie, I just take it into consideration when taking readings, but if I was unaware it would cause my problems that I didnt really have, ie fg readings that are 'higher' than they are supposed to be etc etc
> 
> bah



Hey my mash temp is 66-67 will that effect how low my fg goes? I haven't calibrated prob or hydrometer how do you go bout calibrating the hydrometer 
Thanks
Jamie


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## Nick JD (28/8/11)

What's telling you you should be getting that FG, and do you input your mash temp?


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## jamiefbacon (28/8/11)

Nick JD said:


> What's telling you you should be getting that FG, and do you input your mash temp?



I'm using brewmate and I'm putting in my mash temp it's set at 75% aa is that the norm I'm only getting 50% if I'm lucky by using the calc in brewmate


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## bullsneck (28/8/11)

Are you properly rehydrating the yeast? That may play a part.


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## Wolfy (28/8/11)

Some more questions:
Batch size? Aeration procedures? Rehydration procedure? Cooling method/pitching temps?


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## jkmeldrum (28/8/11)

Wolfy said:


> Some more questions:
> Batch size? Aeration procedures? Rehydration procedure? Cooling method/pitching temps?


I had a similar problem a while back....then someone on this forum asked whether I'd corrected my FG reading to take into consideration the alcohol which skews the final gravity reading.

I'm not sure if that's only when using a refractometer (like I am) or whether it applies to hydrometers as well.

Cos I knew my beers were reasonably powerful but the alcohol % indicated a mid-strength!!!

After the adjustment the FG came down a lot and the alcohol % then made a lot more sense

Molly


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## jamiefbacon (28/8/11)

Wolfy said:


> Some more questions:
> Batch size? Aeration procedures? Rehydration procedure? Cooling method/pitching temps?



Batch size of last one was 19l others were rnd 22 23 liters. Aeration is from pouring out of cube into FV. Cooling is no chill n is at 18 before pitching yeast as I sit it in ferment fridge and let it get to 18. And I've never rehydrated Maybe that's the problem how do u go about it wolfy?


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## bigandhairy (28/8/11)

jbacon said:


> Batch size of last one was 19l others were rnd 22 23 liters. Aeration is from pouring out of cube into FV. Cooling is no chill n is at 18 before pitching yeast as I sit it in ferment fridge and let it get to 18. And I've never rehydrated Maybe that's the problem how do u go about it wolfy?


In a nutshell - calibrate you probe by testing it in an ice slurry (should be zero) snd boiling water (should be 100) take nlte of difference and adjust your readings. Calibrate your hydro using tap water at or about 20deg (depending on your make of hydro) it should read 1000, if not adjust future readings to accomodate. 
Also in a nut shell - warmer mash temps 67-68ish will have higher fg's, lower mash temps say 62-65will have lower Fg's. Generally speaking of course. 
Rehydrate your yeast by adding some dme to some cooled boiled water mixing vigorously. I do it about an hour prior to pitching and aerating regularly before adding to fermenter. 

bah


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## Wolfy (28/8/11)

jbacon said:


> Batch size of last one was 19l others were rnd 22 23 liters. Aeration is from pouring out of cube into FV. Cooling is no chill n is at 18 before pitching yeast as I sit it in ferment fridge and let it get to 18. And I've never rehydrated Maybe that's the problem how do u go about it wolfy?


If you're pitching the full 12g pack from CraftBrewer, it would seem that you are pitching the 'correct' amount of yeast at the right temp, and don't appear to be doing anything noticeably 'wrong'.
Next time you brew, I'd suggest you try both correctly rehydrating it (in lukewarm cooled boiled water only) and providing more oxygen by better/more vigorous oxygenation as both those should help.


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## jamiefbacon (28/8/11)

Thanks guys will have too have a go at Rehydrating the yeast first. Now I think bout it when I use liquid yeast I haven't had a problem with fg. Also do u guys think my aeration from pour out of cube into fv is enough 
Thanks again

Jamie


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## bigandhairy (28/8/11)

jbacon said:


> Also do u guys think my aeration from pour out of cube into fv is enough
> Thanks again
> 
> Jamie


Thats how I do it. Dump it straight in so it chugs and chugs, leaves a big thick head of foam/bubbles on top. Seems to work for me. 

bah


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## Wolfy (28/8/11)

jbacon said:


> ... Also do u guys think my aeration from pour out of cube into fv is enough


No, not really ... which is why I suggested this 20mins before you asked:


Wolfy said:


> ... and providing more oxygen by better/more vigorous oxygenation


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## manticle (28/8/11)

I often use 1 pack of US05 sprinkled directly into 1060+ wort and resulting brews attenuate fine.

Problems I would be looking at: calibration of hydrometer as suggested. Should read 1.000 in 20 degree water (unless calibrated for 15 degrees but the difference will be minimal). Wort sample temperature should also be roughly that or the reading corrected (again not a big deal if it's close).

If, as Molly hinted at, you are using a refractometer then the presence of alcohol will give you a much higher reading. You need to use a conversion chart if this is the case. 

Try dropping your mash temp to 63 - 64 and see if that makes a difference.

Also make sure your thermometer is reading correctly and you are taking a variety of readings to account for hot and cool spots. 66-67 could easily be 70-71 if your thermometer is out or you are only taking readings from one spot.

Are you using a lot of crystal or dextrinous malts like cara-pils? Any unfermentables like lactose?

1024 is unlikely to be finished in a standard, non over dextrined type brew so have you actually tried any rousing tricks? Done any fast ferment tests? Why are you thinking that 1024 is the end?

Finally - unless you have great fear of cold break, try unscrewing the lid of your cube to let air in, screwing it back up then shaking the shit out of it as long as you can stand. Then pour from height. The extra aeration will hopefully help. Nothing wrong with rehydrating your yeast if you do it properly but I doubt that alone is making you finish at 1024.


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## felten (29/8/11)

If you're looking for extra aeration in the cube, try shaking the shit out of the cube for a few minutes before you transfer to the FV.


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## rich_lamb (29/8/11)

As others have said, you should probably be pitching a little more or rehydrating your yeast for best results - same for aeration. But while these things may marginally improve your beer I doubt they would be the main reason for your low attenuation. You aren't pushing the envelope on gravity there...
Do this stuff because it's easy and will eliminate question marks.

Main reason for poor attenuation is the composition of your wort - ie. mashed too high a temp (can get similar results of you use extract and add any maltodextrin). And clearly the calibration of your hyrdo and thermometer could affect it. Measuring gravity at weird temperatures can give strange results, but as you asy you're brew is accurately temp controlled, so not an issue here (unless you measured the SG at higher temp?).


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## jamiefbacon (29/8/11)

manticle said:


> I often use 1 pack of US05 sprinkled directly into 1060+ wort and resulting brews attenuate fine.
> 
> Problems I would be looking at: calibration of hydrometer as suggested. Should read 1.000 in 20 degree water (unless calibrated for 15 degrees but the difference will be minimal). Wort sample temperature should also be roughly that or the reading corrected (again not a big deal if it's close).
> 
> ...



this is a copy of my recipe i followed, dont think there is too much caramalt not sure. I will try shaking the cube more before pouring think this might help a bit 
*10 min IPA*

Original Gravity (OG): 1.058 (P): 14.3
Final Gravity (FG): 1.015 (P): 3.8
Alcohol (ABV): 5.70 %
Colour (SRM): 8.5 (EBC): 16.7
Bitterness (IBU): 30.9 (Average)

91.34% Pale Ale Malt
8.66% Caramalt

3.6 g/L Chinook (11.5% Alpha) @ 10 Minutes (Boil)


Single step Infusion at 66C for 90 Minutes. Boil for 60 Minutes

Fermented at 18C with Safale US-05


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## Ross (29/8/11)

Jamie,

Extremely unlikely it's fermentation issues, almost definately your mashing temps (assuming your measurements are correct). By a cheap mercury thermometer from the chemist & compare the readings at mash temp.
You are already mashing slightly on the high side & being a couple of degrees higher will give you the results you're getting.

There's no requirement to aerate your wort when using dry yeast.

Cheers Ross


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## jamiefbacon (29/8/11)

Ross said:


> Jamie,
> 
> Extremely unlikely it's fermentation issues, almost definately your mashing temps (assuming your measurements are correct). By a cheap mercury thermometer from the chemist & compare the readings at mash temp.
> You are already mashing slightly on the high side & being a couple of degrees higher will give you the results you're getting.
> ...



K ross cheers ill buy one when we i get home next and compare my measurments, and ill mash a bit lower to start with anyway.


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## Lord Raja Goomba I (29/8/11)

I deliberately mash at 68-70 degrees, when I want a beer to finish at 1.020 - assuming the style I want to brew is asking for it. It's likely mash temp, IMHO.

Given I brew sometimes for others who like a sweeter beer, when I want a winter low alcohol dark beer that's a little on the sweet and roasty side, then I mash higher.

Goomba


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