Help me troubleshoot my fermentation

[tekkydave]

Assistance would be appreciated. I just bottled an oatmeal stout after 4.5 weeks in primary. OG was 1.07, FG was a disappointing 1.03, or perhaps a tiny bit lower. Yeast was safale s-04. I don't have a ferm chamber, just the space behind a door that is usually around 63-64. The stout had a nice Krausen, but the airlock never bubbled. I chalked it up to a possible leak in the airlock, and dismissed it. After around 36-48 hours, the Krausen began to drop, as my beers normally do (I'm doing 2.5 gallon batches in a 6 gallon better bottle. I left it to yesterday, and then transferred to my bottling bucket and took a hydrometer reading and discovered the poor FG. I bottled it anyway, as I already transferred it to the bottling bucket. I know I'm risking bottle bombs, so I put towels over and under the cases.

What do you think is the issue? This was only my 6 batch, but the last few didn't have FGs this high.

Also, I should mention this was AG, not extract. And I checked my hydrometer on plain water and it looked fine.

Do you think I fermented too hot, and the yeast petered out before all the sugar was consumed? Any advice would be appreciated, as I was pretty discouraged last night.

 

[TheBaconator]

If you fermented too hot it would probable ferment more vigorously. In that case you normally get a lower FG but stronger alcohol flavors. So I don't think that's what happened. Fermenting too cold can cause a stuck fermentation but I think your temperature range is within what is expected of that yeast. I'm assuming this was one of your first all grain batches, do you know what kind of efficiency you're getting from your setup? What was your mash temp also?

If you mashed at a higher temp +-155f or didn't get great efficiency, having your beer end up around 5% alcohol could just be par for the course. 1.07 is a pretty high OG also, so you would have needed to pitch more yeast than you would for a beer in the 1.05 range.

I'd recommend for next time pitch more yeast and see what kind of efficiency you're getting from your brewing setup. You may need to tweak your processes a bit to improve that.

 

[BradleyBrew]

Do you do AG or Extract? S-04 flocs very fast and needs some additional couragement at times to finish. Also, that yeast does not attenuate that high. Maybe around 67-71% so its going to leave you with a higher FG equating to a "sweeter" beer. With a full sachet of @ 11grams under pitching is really not your problem. My guess is that the yeast is just done fermenting, especially if you did a 100% extract batch. The FG is the nature of all things combined.

 

[BierMuncher]

How did you aerate?

 

[NordeastBrewer77]

yeah, mash temps or aeration are the likely culprits here. 04's not a high attenuator, but it's not that low.

 

[TopherM]

With a starting OG of 1.07, and S-04's average 75% attenuation, you should have an expected FG of 1.0175. You have have had a stuck fermentation, and should have probably tried to rouse the yeast or warm up the wort a bit to complete the fermentation before you bottled.

Bottling at 1.03, I think you are definitely in for some bottle bombs, not to mention a Sweet Oatmeal Stout!

 

[tekkydave]

I aerate with an aquarium pump, but no diffusion stone. I know I need a stone. I think I shook the carboy a bit too, but not a ton. I mashed at 156 for 1hr. I pitched a whole packet, for 2.5 ga batch.

 

[BrewerinBR]

a 1.03 FG is less than 60% attenuation and that is low even for Safale-04. Your fermentation temperatures look fine if that is accurate (63-64). 156 mash is a little high and would get you a lot more non fermentable sugars than say 150 to 153. 11 grams for 2.5 gallons is enough, did you rehydrate the yeast? What was the grain bill? A lot of crystal or other adjuncts would increase the non fermentables and give you a high OG and a high FG

 

[tekkydave]

Heres the recipe

Recipe Type: All Grain
Yeast: S-04
Yeast Starter: no
Batch Size (Gallons): 5.25
Original Gravity: 1.055
Final Gravity: 1.018
IBU: 36
Boiling Time (Minutes): 60
Color: 35
Primary Fermentation (# of Days & Temp): 14days @ 65F
Secondary Fermentation (# of Days & Temp): no

OG 1.055 (80% efficiency, adjust base malt for your system)
IBUs 36
6.75# Pale malt
0.5# roasted Barley (350l)
0.75# chocolate (330l)
0.5# crystal 40
0.5# crsytal 120
0.75# victory
1# flaked oats
2oz Willamette hops at 60
S-04 yeast

Single infusion mash at 156F for 60 min.



Also, the volume that I got into the bottling bucket was 2 gallons, and I primed with 1.75oz of corn sugar

 

[TopherM]

You have something all screwed up here. Expected OG was 1.055 and you got 1.070? Expected FG was 1.018 and you got 1.03?

This was supposed to be a 5.25 gallon batch, and you are stating you only yeilded 2 gallons? Did I read that part right?

 

[tommybjr]

Next time you need to top off to get to your SG. An extra half gallon of water probably would have brought your SG near your expected range. Dropping 40 points, which is essentially what happened, would also bring you closer to your expected FG.

 

[tekkydave]

I have to check my notes again, now that I'm thinking about it, OG may have been 1.062, but definitely not lower than that. As far as my volumes, I'm boiling in a 4 gal pot, I can only fit about 3.5gallons in there without major boil over, then I lose about 1 gal to boil off. Then once in the fermenter, I always lose about .5 -.75 gal to trub and transfer.

Also, as far as the recipe, I halved all of the amounts. I would have put my actuals, but I'm on my wife's iPad, not my computer, where I have my notes.

I put my bottles in a plastic bag, in case of bottle bombs. I think I may be too much of a worry wort(no pun intended) for this