[rdjuddjr]

I brewed a little about a 17 gallon batch 6 weeks or so ago.  I only have 3 kegs so I kegged roughly 15 gallons of beer.  Normally I bottle the remaining beer but this time I thought I would rack it into a 3 gallon carboy and add it to the first empty keg.

Now, it has white circles floating on top.  Anyone know what they are?

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[Village Taphouse]

I'm going to say it's contamination.  Something got into your fermenter and took over.  If you open it and take a whiff... what does it smell like? 

[HopDen]

I brewed a little about a 17 gallon batch 6 weeks or so ago.  I only have 3 kegs so I kegged roughly 15 gallons of beer.  Normally I bottle the remaining beer but this time I thought I would rack it into a 3 gallon carboy and add it to the first empty keg.

Now, it has white circles floating on top.  Anyone know what they are?

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Well my first thought is the carboy had either laten yeast or bacteria and its fermenting the residual sugars. Thats just a guess though. Second guess is that it wasn't done fermenting and when you racked to the other carboy it put any yeasties back into suspension. Again, just a guess.

[RC]

It's mold, which is fungus. Even if it doesn't smell or taste off, it may not be safe to drink. I'd dump it if I were you.

[rdjuddjr]

It doesn't smell bad but I don't plan to drink it.  I think the fermentation was done and generated no CO2 to displace the air.  Mold is probably the best guess.  I wonder what I could have done differently.   I am generally pretty sanitary.   Never had to dump beer before.   Breaks my heart.

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[majorvices]

Looks like mold. It that a secondary? If it is that is way, way too much head space for a secondary. You are inviting oxidation and contamination.

[rdjuddjr]

It is a secondary of "leftover" beer that wouldn't fit into my kegs.  I was hoping to refill one with this beer.  Head space could very well be the problem.  I wonder what else?

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[majorvices]

I don't know what else you need. It looks like mold. Definitely some kind of contamination. At least its just left over.

[rdjuddjr]

Would the mold have grown if I had put a little corn sugar in when racking?

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[RC]

Would the mold have grown if I had put a little corn sugar in when racking?

Did the liquid level in the airlock ever drop below the top of the openings of the inner cap? That's a very common way for molds to ingress, and they'll also get the oxygen they need to grow.

Molds in general are strict-ish aerobes (require oxygen to survive/grow). You have a lot of growth here, which suggests this mold has had a lot of oxygen exposure--again, possibly from an airlock without enough liquid in it?

If there has been enough liquid the whole time, then yeah I think adding some sugar at racking would have consumed and/or driven off the oxygen.

[rdjuddjr]

Thank you very much.   The liquid level in the airlock was fine.  Obviously too much head space.  (Great observation)  so, I needed to clear the air as it were.

Appreciate all the help.

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[BrewBama]

This is all pure speculation:

Mold usually takes a long time to grow on beer so as long as you're not leaving it in the fermenter for too long, you shouldn't have this issue.

Based on your cleaning , sanitation, and other handling techniques, I think you crossed that line. Someone else’s timeline could be longer or shorter based on their techniques.

While you did have a lot of headspace and the mold may have been in the carboy to begin with, my vote is you held it in the carboy too long.

My guess is your airlock is attached to your carboy with a stopper.  That stopper allowed CO2 out and air in (based on the law of partial pressure) over the lengthy time you were holding it in the fermenter. That air that entered brought hitchhikers in the form of mold.


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[erockrph]

My guess is your airlock is attached to your carboy with a stopper.  That stopper allowed CO2 out and air in (based on the law of partial pressure) over the lengthy time you were holding it in the fermenter. That air that entered brought hitchhikers in the form of mold.

If the only gas to be exchanged across this barrier was due to diffusion based on a pressure differential, then you won't have any microbial hitchhikers. Microbes aren't dissolved in the air, they travel on dust or liquid droplets. So while you may see gas exchanged across a permeable barrier, you won't pick up microbial contamination in that manner. If there was a leak that allowed direct air flow, then you have a potential contamination risk if the opening and flow are sufficient to allow particulates to pass through.

[ynotbrusum]

It only takes one spore to contaminate a batch with mold over a long enough time.  Areas like basements provide the perfect environment for mold to hang out in...keep oxygen ingress to a minimum to help to avoid mold spoilage.  We are in a constant battle at the microbial level for our fungus to outcompete the unwanted invaders.  Storage in bulk with oxygen exposure is the worst environment, for sure, even if free of unwanted microbes.

[BrewBama]

It only takes one spore to contaminate a batch with mold over a long enough time.  Areas like basements provide the perfect environment for mold to hang out in...keep oxygen ingress to a minimum to help to avoid mold spoilage.  We are in a constant battle at the microbial level for our fungus to outcompete the unwanted invaders.  Storage in bulk with oxygen exposure is the worst environment, for sure, even if free of unwanted microbes.

+1. Basements and closed moist containers (aka fermentation chambers) are great places for mold. 

As said, one speck of dust or droplet laced with a spore, given enough time, can grow a colony.

IMO, when the beer is finished package it.