High Gravity low attenuation?

[Dougie63]

I brewed a High Gravity Stout for the second time and this time I lowered the temp in a cooler with ice packs 2x a day. Water temp is a steady 64 deg F and bucket temp is about 68 according to the stick on thermometer. That is the only difference from the last batch and this batch did not get the violent fermentation with krusen comming up into airlock and such.Is it because of the temp or do I have a problem with the yeast? It is fermenting, bubbles seem to be slowing now day 4, but nothing like the last one I plan on keeping in primary for 2 weeks then transfering to secondary for 2 more weeks or should I get more yeast and add more?

 

[Nateo]

It's normal for attenuation to drop as gravity increases. This is why people use pitching rate calculators based upon OG, like this one:
mrmalty.com/calc/calc.html

I wouldn't rack into secondary at all, but if you do, I definitely wouldn't do it until your gravity is where you want it to be. The beer is on its own schedule, not yours.

 

[lumpher]

I brewed a High Gravity Stout for the second time and this time I lowered the temp in a cooler with ice packs 2x a day water temp is a steady 64 deg F and bucket temp is about 68 according to the stick on thermometer, that is the only difference from the last batch and this batch did not get the violent fermentation with krusen comming up into airlock and such is it because of the temp or do I have a problem with the yeast? It is fermenting bubbles seem to be slowing now day 4 but nothing like the last one I plan on keeping in primary for 2 weeks then transfering to secondary for 2 more weeks or should I get more yeast and add more?

tried to read this but very little punctuation, so it became 1 runon question and i had very little idea what was being asked and got more confused the more i read it especially with the misspellings so if you could ask you questions with a few more periods and commas and starts and ends of sentences it would be more clear.

 

[Nateo]

agree with lumpher ^

 

[dave104]

I have a similar problem, I am currently on my fourth batch of home brewing, but I cannot seem to get the FG down as low as I think it should be.
Current batch is 2.5 gallons of a Porter. OG was 1.074 (the recipe-which I followed very closely-said it should be 1.065) and after a week and a half, with the bubbling having stopped after six days, the gravity is now 1.031. It looks and smells great, but the attenuation calculates to 58%. I used Wheat DME, Dark LME, three grains, two types of hops, and most of a tube (for 5 gallons) of liquid Edinburgh Ale Yeast. The yeast practically burst out of the tube when I opened it, so I figure it was live, I am pretty sure I did a good job aerating the wort by sloshing it around for a couple of minutes, temperature has been a pretty constant 68-70 degrees, and it bubbled longer than my other batches have (they have usually bubbled for only a day, this time it went six before stopping). I will let it go another couple of days before racking it to secondary (the recipe says to leave in primary 1 - 2 weeks before racking to secondary), but if it is true to past experience it will not get any lower.
My previous batches (all from LME) were a Medium Amber Ale (OG 1.052, FG 1.021) a Lager (OG 1.051, FG 1.014) and another Ale (OG 1.055, FG 1.021) It seems that the Lager got pretty close (which is strange because the temperature was a little high at 66ish) but the Ales have had FGs about .007 higher than expected and this time looks to be even higher. I am concerned about bottle bombs (although I have not had any yet)
Anyone have any advice or suggestions?

 

[Germelli1]

Dave, my instinct told me that the use of Dark Extract in conjunction with 2 specialty grains would yield a very high final gravity. Without know the manufacturer of the extract, or the quantities of everything, it is hard to troubleshoot!

 

[dave104]

Thanks for responding. I believe the DME (1 lb) manufacturer was Northwestern the LMR (3.3 lbs) Briess, and the yeast White labs. The speciality grains were chocolate (.5 lb), Dark Crystal 120 (.25 lb), and Black Malt (.25 lb). The hops pellets were Chinook (.5 oz for boiling), and Goldings (.25 oz for boiling and .25 oz finishing).

Despite the frustrations, I am really enjoying my new hobby. Only problem (if it is a problem) is that my beer consumption has increased a whole lot.

 

[Germelli1]

Thanks for responding. I believe the DME (1 lb) manufacturer was Northwestern the LMR (3.3 lbs) Briess, and the yeast White labs. The speciality grains were chocolate (.5 lb), Dark Crystal 120 (.25 lb), and Black Malt (.25 lb). The hops pellets were Chinook (.5 oz for boiling), and Goldings (.25 oz for boiling and .25 oz finishing).

Despite the frustrations, I am really enjoying my new hobby. Only problem (if it is a problem) is that my beer consumption has increased a whole lot.

Haha yes, I only drink on days I run or work out as a rule to avoid increasing the waste line. I am also in the washed up athlete stage of my life and am nowhere near my original playing weight haha.

Let me do a little research and get back to you in a few minutes!

 

[Dougie63]

after 2 weeks in the primary I transfered to secondary gravity was 1.030 OG was 1.078 I plan on 2 weeks in the secondary and then bottling, Ill do a gravity check first and if it goes down more I may give another week or so

 

[dave104]

after 2 weeks in the primary I transfered to secondary gravity was 1.030 OG was 1.078 I plan on 2 weeks in the secondary and then bottling, Ill do a gravity check first and if it goes down more I may give another week or so

Me too. An update on my Porter. OG was 1.075, I expected a FG of 1.019 but the actual FG was 1.026 after a little over a month between primary and secondary. I bottled, but kept the bottles in the plastic buckets to cut down on the cleanup in case anything exploded. Nothing did, it all came out fine. A little sweet, but not too much so (I used Maple sugar for priming). After three weeks in the bottles, I doubt any will explode now.

So here is my question:
Where does the percentage of fermentable sugars come in when calculating an expected final gravity? When calculating the expected FG based on OG readings, do you take fermentability into account or not.
For example, I now have in bottle conditioning a batch for which I used yeast with (I think) an expected attenuation of 75% to ferment 4 lbs of barley LME with a fermentability of 75% and 1 lb of rice malt with a fermentability of 100%. Would the calculations for the expected FG points be:
0.25 x OG points [which would count all fermentables the same]
or
0.25 x ( (0.75 x 0.80 x OG points)+(1.00 x 0.20 x OG points) ) [which would differentiate between the barley and rice fermentability]

Would it follow that when using barley LME with a 75% fermentability, and a yeast with 75% attenuation, I should calculate the FG points = 0.75 x 0.75 x OG points ? So, an OG of 1.050 would have an expected FG of 1+((.050x.75x.25)=1.010.

For my current batch, the OG was 1.052 and the FG was 1.021. I had expected (from the on-line calculator) a FG of 1.015. This seems typical – so far all of the ales I have done (5 batches) have missed the expected FG mark by about .007 (high). My concern is that I am getting significantly less attenuation than I should get, even though I haven't yet seen any bottle bombs. (Well, I did have one in the last batch, but I'm pretty sure it was due to a scratched bottle - nothing else in the batch exploded)

 

[unionrdr]

Adding crystal malts & the like will increase the un-fermentable sugars. That'll give a higher FG. I've had no trouble getting a 1.050OG down to 1.012-1.010FG By using LME & DME with hops,no crystal malts. Other than what may be in the extract.