Suckback in carboy?

[Uncomfortabrew]

Hi, my yeast lock, which i filled yesterday is almost completely emptied out already - and only one way it could have went (down the carboy)
I wonder what have happened here? I can take some pictures if that would help
It have only been fermenting for about 3 weeks and it stands i my cellar with a pretty stable temperature around 12-15 degrees

Thank you for the help

 

[Blacksmith1]

When you say filled, do you mean to the top? Because there is a fill line which is about 1/3 of the way up from the bottom of the chambers on the S type and about half way up on a three peice. The only reason one should " suckback" is if there is negative pressure in the carboy. Any fermentation at all should cause positive pressure by creating CO2. Vigorous fermentation could in theory blow your liquid out of the top.

 

[wasully]

No fermentation and a sharp temperature drop could do some suckback.

 

[Uncomfortabrew]

This is my carboy with the built in yeast lock
https://www.amazon.de/Universelles-Weinballon-Gärsystem-Glasballon-Einmachtopf/dp/B014SX9Q2C
And there have not been any significant temperature changes, so i am bit confused of what had happened?

 

[RPh_Guy]

It looks like that provides a lot of surface area for evaporation.. maybe that's just what happened.

Alternate theory.... Fermentation generates a lot of heat. After fermentation is done, CO2 production stops and the vessel starts to cool; contraction causes a negative pressure.
However there isn't normally enough of a temperature change to cause suck-back after fermentation and there is usually still residue CO2 being released. Was the fermenter insulated somehow? Inside a box or wrapped in a blanket or something?

 

[Blacksmith1]

I have never seen one of those.....

 

[CKuhns]

Small children or Aliens. Things mysteriously happen around both groups and no-one seems too know what, how or why it happened.

Temp change after ferment is done
Crack in the airlock

Ask the kids...

 

[Uncomfortabrew]

It looks like that provides a lot of surface area for evaporation.. maybe that's just what happened.
Was the fermenter insulated somehow? Inside a box or wrapped in a blanket or something?

I thought it might have been evaporation aswell, but i put water back in the lock, and more than half was gone the day after, which is surely not because of evaporation.
And it is not insulated at all, then cellar/basement have had a window open a bit, but i do not think that have caused any major temperature changes.
And now, the water level is stable and got CO2 blops in the yeastlock - only been 4 weeks, so think it would be a bit fast if it was stopped fermenting already

But yes, probably it is just aliens

 

[Maylar]

I have never seen one of those.....

Looks just like a Big Mouth Bubbler - though I've never seen an 8 Ltr / 2 Gal one

 

[Uncomfortabrew]

Still no ideas why the suckback is happening?
Gonna change the yeast lock with an s-shaped one
But i have been kept having the suckback multiple times now

 

[bucketnative]

I have a similar airlock that was made for Mason jar lids. You would be surprised at how much will evaporate; especially on a dry day.

Otherwise, how stable is your temperature? If it gets warm during the day, air will be expelled through the airlock. Then if it cools down much at night, the pressure in the fermenter will drop and the water can be drawn in as air from the atmosphere tries to equilibrate the pressures.

 

[Uncomfortabrew]

I dont have a way to watch the temperature, but my guess is that its pretty stable - maybe some smaller changes during the night in the cellar its stores in.
It is not evaporation as i can see the water level in the lock rising towards the hole to the carboy - so definitely suckback
The fermentation is done and have been for some time and it still does the suckback but think i will go with your theory bucketnative