What's occuring, fermenting still going on 11th day

[bigchris]

Brewing my normal recipe. I use a closed FV with airlock and bubbling is nearly always finished by the 7th day, sometimes 6 days. This brew is now on its 11th day and still bubbling about once every 3.5 minutes, really slow. Same yeast as normal US-05, even the same grains and O.G. 1.042.

Being a bit OCD and loving data I often record the bubbling rate and graph it. here's a typical graph and the graph of the latest, slow, brew. Both at 19 degrees.






Is this a mashing issue?

Rgds
Chris

[barney]

Temperature the same?

[IPA]

I had this once a long time ago and it was due to a bacterial infection. Hope this is not true in your case. I had to tip it down the toilet with tears in my eyes!

[super_simian]

Bubbles do not equal yeast activity. Check your gravity son!

[bigchris]

Bubbles do not equal yeast activity. Check your gravity son!

Well thanks SS, you're right, of course. I used to go by gravity when fermenting without the airlock. Become lazy I guess, recently, just watching the bubbling for an end to fermentation.

Checked the gravity this morning, 1.008, so looks like it has finished. Will probably rack this off into the keg this afternoon.. gravity sample tasted pretty good too so happy so far.

[Eric]

Lovely bit of data, thank you.
I too found S05 goes on a bit compared with some yeasts, but also not as much as others.

[Martin G]

Atmospheric pressure did drop steadily during the period at the end of your graph, wonder if that had an effect? Although given the mention of infection, 1.008 would be on the worrying side of low for me with my brews, but I have not used that yeast so perhaps that yeast normally goes low.

[bigchris]

Atmospheric pressure did drop steadily during the period at the end of your graph, wonder if that had an effect? Although given the mention of infection, 1.008 would be on the worrying side of low for me with my brews, but I have not used that yeast so perhaps that yeast normally goes low.

A man after my own heart. See some unexpcted data and try to identify the cause. I had not considered atmospheric pressure, but now you mention it, I suppose it could have an effect, partly by allowing any gas above the beer to expand out of the airlock to equalise pressure, and partly allowing more disolved gas to be released from the beer.

Checked FG again when kegging, definately 1.008. What I've learned from this is that once my bubbling graph begis to end its sharp descent, around 3 bubbles per minute, I need to start keeping an eye on the FG.

It's generally been a principle of mine not to open the FV any more than necessary.

The kegged beer tastes pretty good, so I'm relieved that it does not seem to be infected.

[bigchris]

Martin, you sparked my thinking, but it seems not to be the case, here's the graph with atmospheric pressure plotted from the NPL records on their website.

[super_simian]

1.041 to 1.008 with US05 sounds totally plausible to me. Boom, problem solved.

[Martin G]

Martin, you sparked my thinking, but it seems not to be the case, here's the graph with atmospheric pressure plotted from the NPL records on their website.

Well I, wouldn't want to argue with NPL!

[AdyG]

I did a AIPA with US-05 and it fermented for about that time too, it went for about 1056 to 1012 (if I remember rightly). After about 11 days I transferred to an another FV to dry hop and rest it for 3 days, from brewing to kegging was 14 days... and it was my best beer yet! US-05 does seem to ferment for longer so I wouldn't worry about it.

My second batch of IPA with simcoe hops has just been transferred to a secondary FV after exactly 11 days of good fermentation, temperature was also about 20 degrees and it's at 1012, so again I am happy with the results. Quick slurp from the trial jar indicates that this will be another cracking IPA!

Let us know how it tastes when ready!

[Rick_UK]

A bubble every 1 minute or more is an indicator its done. Obviously the hydrometer is your definitive answer.