Black Mold Growing or StarSan reaction?

[klamz]

So I ferment in 6.5Gal glass carboys with blowoff tubes. My Belgian Dark strong ale tasted great when sampling it, whoever I did notice that the crusty dry krausen at the neck of the carboy turned black resembling black mold.

Has anyone seen this before? I do, from time to time, get band aid medicinal infections in my brews and could never figure out what it is. Perhaps this is the cause? if so why is this happening? I do suspect that it could be the sanitizer getting sucked back into the carboy and dripping onto the yeast creating some discoloring.

I always get nervous when changing a 3 piece air lock with a blow off tube and visa versa. I usually dowse it with starsan while it's dripping wet and a little drips back into the brew. Should I be worried about that?

Thanks!

 

[cannman]

what yeast strain did you use?

 

[unionrdr]

It sounds like the crud the krausen leaves behind to me. The darker beer would give it a darker color as it dries.

 

[klamz]

Its the westmallen yeast i think 3787

 

[dwhite60]

Bottled a barley wine last Thursday night. It had
a black ring around the inside of the carboy neck.
Washed out pretty easy though.

All the Best,
D. White

 

[singybrue]

The starsan isn't going to hurt your beer.
How old is your blow-off tube? It's good to replace the plastic stuff semi-regularly as a precaution.