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High Final Gravity

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HalfWit

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Hi peoples, I'm trying to workout why I have not reached my required FG in my last two brews. I have tested my hydrometer and thermometers, and all are OK. This is my last recipe. It has been in the fermenter for 24 days. The yeast started strongly but after 14 days it only dropped to 1.037 and after rocking the fermenter for the last week and a bit in has only got down to 1.035. I was planning on watering down when kegging. It tasts beautiful.


Type: All Grain
Date: 10/03/2013
Batch Size: 48.70 L
Brewer: Damian Boil Size: 57.00 L Asst Brewer: Boil Time: 60 min Equipment: BIAB Taste Rating(out of 50): 35.0 Brewhouse Efficiency: 70.00 Taste Notes:
Ingredients

Amount Item Type % or IBU
12.50 kg Pale Malt (2 Row) UK (3.0 SRM) Grain 76.22 %
1.20 kg Black (Patent) Malt (500.0 SRM) Grain 7.32 %
0.90 kg Caramel/Crystal Malt - 80L (80.0 SRM) Grain 5.49 %
0.60 kg Pale choc Malt (200L) (180.0 SRM) Grain 3.66 %
12.00 gm Northern Brewer [7.00 %] (60 min) Hops 3.6 IBU
100.00 gm Goldings, East Kent [5.00 %] (60 min) Hops 21.5 IBU
1.20 kg Milk Sugar (Lactose) (0.0 SRM) Sugar 7.32 %
3 Pkgs Whitbread Ale (Wyeast Labs #1099) Yeast-Ale


Beer Profile
Est Original Gravity: 1.070 SG
Measured Original Gravity: 1.070 SG Est Final Gravity: 1.020 SG Measured Final Gravity: 1.035 SG Estimated Alcohol by Vol: 6.58 % Actual Alcohol by Vol: 4.57 % Bitterness: 25.1 IBU Calories: 696 cal/l Est Color: 44.3 SRM Color: Color
 

scmgre

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are you pitching enough Yeast 48 litres is a large batch how big's your starter? Whats your mash temp? if it's high you will get more body but a higher FG. Lactose is not fermentable which adds to the high FG but adds the sweetness to your milk stout.
 

HalfWit

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My mash temp was 68C. I made a 4L starter with the three yeast packets but I don't think I let it ferment out. It looked like a lot of yeast at the bottom of the flask.
 

treefiddy

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I don't suppose you're using a refractometer?

SG 1.070 with an refrac reading of 1.036 means an actual FG of 1.014.
That seems a little low for a beer like that but it's worth ruling out.
 

HalfWit

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I wish.Unfortunately, just a hydrometer.
 

barls

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68s fairly high up there and will leave a fair bit of unfermentable sugars.
most aim for 65 or so. i only go that high when i doing my milds and low alcohol beers
 

HalfWit

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Thanks guys, I will aim for 65C and prepare my starter better next time. Hopefully that fixes the problem. Do you think it would be safe to bottle some? I was planning on kegging and than putting into bottles but don't want bottle bombs.
 

sponge

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What temp has it been fermenting at?

Might be worth giving it a gentle stir with a sanitised spoon and letting it warm up a couple of degrees to see if it can drop a bit more..
 

joshuahardie

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My milk stouts have about the same percentage of lactose in it, and mine drop from 1062 to 1024

So yours sounds underattenuated but still given the high mash temp and pitching rate it is probably within limits.

If you like the taste, roll with it, and just adjust those variables next time.
 

HalfWit

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I kept the temp right on the money at 19.5C.
 

Dan Pratt

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please pardon my ignorance....why did you use 3 packets of wyeast to make a 4 litre starter? your LHBS must love you.

1 packet at 1.5, then step to 3 up to 4 litres would getthe same amount of yeast right?
 

djar007

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Do you use Yeast nutrient in your starter? I have read that lme starters will need yeast nutrient to get them going. But if it is an all grain wort starter that it will not.
This what John Palmer had to say about it.
If you experience stuck fermentations or low attenuation, and you have eliminated other variables such as: temperature, low pitching rate, poor aeration, poor FAN, age, etc., then lack of necessary minerals may be a significant factor.
and here is the link. May not be the cause but I do love to venture an opinion, even if it isnt my own. :D
 

doon

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I make dme starters all the time and never use nutrients and never have a problem. Not sure if dme is going to make a difference over lme
 

TNT650R

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I'm agree with pretty, if you use 3 packets for the starter...you waste a lot of money!!

for the final gravity....
the mash temperature is good
the starter enough and yeast live
the fermentation temperature ok...

I think that u have a problem with aerating..it is an essential part of brewing because the yeast used O2 during the cell reproduction...I don't know your method of aeration but with that volume you can stir vigorously for some minutes, it is a rude way but the best for small ammounts of must (150L..).
I hope that you can understand what I mean.
 

dicko

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1099 is renown for dropping out quickly and rousing the yeast is very important to keep it going.
Giving the brew a hit with O2 or an aquarium pump about 12 hours after pitching is a good practice.
3 packets of yeast should have been close to the required amount provided that the yeast was in good condition and not passed its date. A healthy starter is always the best option. Mash ph is worth checking as well as I believe this may cause problems with attenuation. As said above, yeast nutrient cant be forgotten either,
That yeasts attenuation is 68 to 72% so at 68% it is not that far off.
Cheers
 

HalfWit

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I just purchased three packets of yeast because my time schedule was tight. The yeast was only about a week old. Fresh off the boat, as they say. I adjusted mash PH and added yeast nutrients to the mash, not the starter.
I used a siphon spray wort aerator. http://www.craftbrewer.com.au/shop/details.asp?PID=968 It does a good job, i reckon.
I'm yet to work out the measuring of yeasts attenuation thingy but I will look into that soon. I'm glad to hear I got closeish to the mark.
 

dicko

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Add your nutrients to the boil in the last 10 minutes for maximum effect.
I have used 1099 twice in my years of brewing and while it flocks out and leaves the beer brilliantly clear it is a real bugger for dropping before it is finished its job.
If as you said the beer tastes ok and is too you liking and fermentation has definately stopped then go ahead and bottle it and enjoy.

Cheers
 

tdh

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Hi Halfwit.
Your attenuation is only 50% and therefore I's be reluctant to bottle a beer that could slowly keep fermenting in the bottles.
I'd keg rather than bottle, PET bottles at a pinch.

To work out attenuation -

OG = 70 points
Current gravity = 35 points
Gravity drop = 35 points
35/70 = 0.5
0.5 x 100 = 50%


OG = 70 points
Current gravity = 21 points
Gravity drop = 49 points
49/70 = 0.7
0.7 x 100 = 70%

Capito?

GT
 

Hippy

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For a high gravity beer like that you'd be better off using pure oxygen to oxygenate your wort as the maximum amount you'll get from air is about 8ppm of O2 and the yeast will need over 12ppm of dissolved O2 for optimum growth and fermentation.
So even if your wort spray aerator can give you 8ppm you will still have problems with underattenuation. Also as stated above oxygenating again at 12 hrs is advisable.
 
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