Fermentation, Fast then Stopped then Slow?

[Luxo_Aussie]

G'day All,

I just wanted to see if this looks right to the other brewers here. So I have a Tilt & it's great for up-to-minute readings during fermentation but after having a few bottles which have been over-carbonated I have been letting my beer go for warmer/longer to see the effects. Below is a Pacific ale left fermented with Nottingham, but I have had a few others with different yeasts like this which have had similar profiles

There's the speedy take off as normal but then it seems to get stuck at 1.019ish for three days and only picks up when I start ramping up the temperature past 20 degrees. From there it's super slow as well and now it's been a week since I started ramping and still dropping a bit each day. People online have been commenting on beers such as 'grain to glass in one week' ect so I'm wondering why I seem to have this strange profile which just crawls along. Could this be under pitching or maybe I need to be oxygenating before pitching? Keen to know what this might mean to speed up my future ferments.

Cheers & Thanks!

 

[Luxo_Aussie]

Here's another one, gets stuck around 1018 & then finishes at 1009

 

[fermento_b]

Have you tried confirming the measurements with a second method? Manual hydrometer or refractometer?
If you have changed your TILT battery it may need recalibration. Multi-point calibration is best.

I have seen ferments stall at lower temperatures, but your ferments there aren't low (unless for kveik or saison). Nottingham should power through at lower than those temps and your brews there just aren't cold enough there to cause concern. Though sudden drops might stress a yeast. Too much pressure can do it too.

What was pitching temperature? And the pitch rate? How big is your batch? Your O.G. isn't that high to be concerning. Pitch rates can be effectively lower than expected if the yeast is old (temperature of yeast storage impacts too).

Aeration? Usually not needed if using dry yeast, its more for liquid and recast yeast, or really high O.G. So the situations you would consider making a yeast starter for anyway.

 

[HLBrew]

I just had a similar experience recently (not using a wifi hydrometer) where the fermentation was super slow and on and off at the end. I discovered that my temp controller was reading a few degrees below the temp of the liquid. Haven't determined whether its because of the position and insulation of the probe, or whether calibration was out but the outcome was that my fermentation temp was too low. Even when I started cranking it towards the end to get the last bit of attenuation and diacetyl cleanup, I was well below where I thought I was temp wise.

 

[Luxo_Aussie]

Thanks for the feedback, I think I've worked out what caused this issue as its happened in my bottles as well, see here

Something wild (which didn't have any aroma/taste apart from reduced malt character) got into the fermenter which kept things fermenting long after it should have stopped. I have since changed my process and the past 3 batches are all looking to have a more correct level of carbonation.

 

[Radmax]

Have you tried confirming the measurements with a second method? Manual hydrometer or refractometer?
If you have changed your TILT battery it may need recalibration. Multi-point calibration is best.

I have seen ferments stall at lower temperatures, but your ferments there aren't low (unless for kveik or saison). Nottingham should power through at lower than those temps and your brews there just aren't cold enough there to cause concern. Though sudden drops might stress a yeast. Too much pressure can do it too.

What was pitching temperature? And the pitch rate? How big is your batch? Your O.G. isn't that high to be concerning. Pitch rates can be effectively lower than expected if the yeast is old (temperature of yeast storage impacts too).

Aeration? Usually not needed if using dry yeast, its more for liquid and recast yeast, or really high O.G. So the situations you would consider making a yeast starter for anyway.

When you say "too much pressure" are you talking about too small an airlock or too much liquid in one container or something else? Thanks

 

[fermento_b]

When you say "too much pressure" are you talking about too small an airlock or too much liquid in one container or something else? Thanks

I mostly mean for home brewers fermenting in a pressure vessel, with a spunding valve to control the pressure, and a second pressure relief valve for safety.

Non pressure vessels don't build much pressure from depth, but it's about 1.5PSI per S.G. per meter.

Example: Doing a gravity ferment in a 118L Kegmenter, one meter deep into a 1.066 s.g. wort will have about 1.6psi more pressure than the top.
1.6 psi probably not going to be an issue for most brews, but if the pressure kit is attached, and configured borderline too high already, it's something to think about (edit: for commercial brewers with multistory tanks)

Not to mention, if your wort is 1m deep in a 118L Kegmenter, you probably won't have enough head room for a vigorous ferment and may clog the spunding valve.

EDIT: (fixed decimal places which wildly overstated the pressure issue cheers @elmoMakesBeer).

 

[Radmax]

Interesting. Thanks

 

[elmoMakesBeer]

Non pressure vessels don't build much pressure from depth, but it's about 15PSI per S.G. per meter.
Example: Doing a gravity ferment in a 118L Kegmenter, one meter deep into a 1.066 s.g. wort will have about 16psi more pressure than the top.
16psi probably not going to be an issue for most brews, but if the pressure kit is attached, and configured borderline too high already, it's something to think about. Not to mention, if your wort is 1m deep in a 118L Kegmenter, you probably won't have enough head room for a vigorous ferment and may clog the spunding valve.

I do hate to be that annoying guy, but actually the pressure in a non-pressurised vessel is actually much less. One atmosphere, or roughly 15psi (or ~100 kPa) is the pressure at about 10 m (not 1 m) depth of water (sg = 1). So in your example the gauge pressure at the bottom of the vessel would only be about 1.6 psi (11 kPa), and the average gauge pressure (at mid-depth) would be half that.

 

[fermento_b]

Haha .. cheers. Right you are Elmo! Im off by factor of ten. Memory aint what it used to be.

Not sure what the protocol is, but I know someone will read what i wrote and remember the wrong bit so I will leave an edit note.