Twist on the "Is it done fermenting" question

[DamonInPHX]

I've searched the forums, and haven't run across this situation.

I brewed a pair of 5 gallon IPAs, using the following ingredients:
8# 2 Row Brewers
3# 2 Row Pale
1# Caramel

3 ounces Citra at 60/15/5 in one, and 3 ounces Simcoe at 60/15/5 in the other. Both dry hopped with 1 ounce Falconers Flight in 2ndary.

Primary for 3 weeks at 65, secondary for a month with dry hops at 65 (busy schedule).

OG Brix was 15 in both. FG Brix was 6.8 in both, measured at racking to secondary.

After a month in secondary, they both remained at 6.8, but the airlocks in both were still occasionally bubbling (on a LONG scale of minutes), and there was definitely (light) activity in both. Hops were rising, sinking, but gently.

So, the (possibly stupid) question is, is it possible for a batch not to be completely fermented out even when the 3-days-apart gravity reading rule is in effect? This goes against intuition and everything I've read here, but the airlock and physical activity leads me to ask.

Apologies if this has been discussed and I just haven't found it. I went through pages of search results, and couldn't find this scenario.

Thanks!

 

[Schnitzengiggle]

I've searched the forums, and haven't run across this situation.

I brewed a pair of 5 gallon IPAs, using the following ingredients:
8# 2 Row Brewers
3# 2 Row Pale
1# Caramel

3 ounces Citra at 60/15/5 in one, and 3 ounces Simcoe at 60/15/5 in the other. Both dry hopped with 1 ounce Falconers Flight in 2ndary.

Primary for 3 weeks at 65, secondary for a month with dry hops at 65 (busy schedule).

OG Brix was 15 in both. FG Brix was 6.8 in both, measured at racking to secondary.

After a month in secondary, they both remained at 6.8, but the airlocks in both were still occasionally bubbling (on a LONG scale of minutes), and there was definitely (light) activity in both. Hops were rising, sinking, but gently.

So, the (possibly stupid) question is, is it possible for a batch not to be completely fermented out even when the 3-days-apart gravity reading rule is in effect? This goes against intuition and everything I've read here, but the airlock and physical activity leads me to ask.

Apologies if this has been discussed and I just haven't found it. I went through pages of search results, and couldn't find this scenario.

Thanks!

Could be an infection, could be off-gassing.

If your sanitation is on par, then more than likely your beer is just off gassing, or gas trapped under the hops (leaf I hope) are being jarred loose on occasion.

Anything is possible, but the simplest explanation is usually the correct one.

 

[beninan]

There will be some CO2 that will have been absorbed into the beer during fermentation. It's probably the CO2 is slowly bleeding off causing it to bubble. I'm sure if you take a sample, you will feel a very slight amount of carbonation. Also changes in atmospheric pressure will cause a differential in pressure between the fermenter and atmosphere. So bubbles in the airlock should be ignored.
If the gravity is stable, it is done.

 

[DamonInPHX]

Could be an infection, could be off-gassing.

If your sanitation is on par, then more than likely your beer is just off gassing, or gas trapped under the hops (leaf I hope) are being jarred loose on occasion.

Anything is possible, but the simplest explanation is usually the correct one.

Thanks, Schnitzengiggle!

I'm insanely OCD about sanitation, and I StarSan the heck out of everything that gets near my beer. Not to say that infection is an impossibility. SMelled good though, just like the others I've done with the same recipe. Didn't taste though.

Dry hop was pellets, not leaf (should have mentioned that). Mashed at 154 is another detail I was going to edit in.

Could be off-gassing. One of the reasons I ask is, I've been having issues with my IPAs gushing as they age (2 months +). So I really want to make sure I'm getting a good finish before I feed the yeast some more. Is 3.4 ounces/5 Gal too much for an IPA with that recipe?

Appreciate the response!

 

[Schnitzengiggle]

Gushing could be from over-priming, incomplete fermentation, or once again an infection.

Some infections will have little effect on flavor in the short term, so it is a possibility.

Keep an eye, and taste when sampling to weed out an infection, it could be something as simple as a piece of racking hose. I'm not trying to worry you but if you have consistent gushers, considering fermentation is complete, and you are weighing your priming sugar to match your co2 volume, then something might be amiss.

Just keep a close watch.

But to reiterate, the simplest explanation is usually the correct one.

Cheers!

 

[day_trippr]

OG Brix was 15 in both. FG Brix was 6.8 in both, measured at racking to secondary.

That's some gawdawful attenuation. What was the mash profile and the yeast used?

My guess is the yeast are trying like hell to digest some complex sugars...

Cheers!

 

[step]

That's some gawdawful attenuation. What was the mash profile and the yeast used?

My guess is the yeast are trying like hell to digest some complex sugars...

Cheers!

Yeah, that sounds like some under-attenuation. I think the next questions should revolve around what yeast and how much.....???

 

[DamonInPHX]

Safale US05, 1 pkg each batch, pitched on top. I've switched to starters on stir plate for later batches, which really seems to kick-start the fermentation, so hopefully that helps.

Brix was measured with a refractometer, not hydrometer. Another detail that will definitely help.