Something stupid just happened 😡

I put my 5 gallon carboy in a refrigerator last night to cold crash.  Everything looked good this morning, but at 6pm, I realized I probably should have replaced the blow off tube with a airlock.  The blow off tube back siphoned about 600ml of StarSan into the carboy.  I had  1000ml flask with starstan that the blow off tube released co2.  Now what? Down the drain?

Never throw it out until you’ve finished. It may not have much effect.

The Starsan was mixed with water at the appropriate labeled rate.

I think you will be alright. Might have slightly lowered your pH but that’s a very small amount of Star San.

Even if it is crap, bottle some and share it with your homebrew club as a lesson learned.  Bad beer can be just as entertaining as good beer.

I’ve done it, no problem, lesson learned.

Same here. Aside from a pH hit, should hopefully be ok.

I haven’t got into checking ph yet, but I know that the town tap water is around 9.

I wouldn’t worry too much about it. I’ve sucked up more than that in one fermenter and none in the other of a 10 gallon batch. There was no real difference between the two. My guess is that your beer will still be good… still drinkable at worst.

Is a backsiphon common with blow off tubes once fermentation quits?

Its a function of your crash creating suction into the fermentor as the beer chills. It can still happen with an airlock as well. Have seen suggestions to just cover with foil when crashing to eliminate this, but then you get oxygen sucked into the fermentor. A slow chill rather than a crash can help, but may still cause suck back

Yo can keep the blow-off tube. Kick it off from the flask, fold it and hold it with a clip like this:

https://www.shutterstock.com/es/image-photo/black-paper-clip-isolated-on-white-149888795?src=fQZFqoFeDKYGQOaA4iZYJg-1-17

Nothing’s gonna come in.

I have no issues with this using an old school S airlock.

I think that’s what I’ve read here as well, I just don’t use them myself as I like the ease of draining and cleaning the three piece units

The issue with the S-type airlocks, and any airlock/blowoff tube, is that it still allows oxygen into the fermentor when cold crashing. When I cold crash in a carboy, I swap the airlock out for a solid stopper.

That being said, I find cold crashing to be much more convenient after racking to a keg.

I also use an S-type airlock when cold crashing but I also replace the star-san in the air lock with cheap vodka or clear rum. This way if it does suck back I know it won’t hurt anything, but come to think of it, I don’t think I have ever had one suck back. I just cold crash by sticking the carboy into my spare beer fridge.

Yep, same here. Takes suck back out of the equation.

While it takes suck back out the equation it adds all the suspended yeast.  ;D

Which will help prevent oxidation when transferring, and will settle out in the keg anyway. Pull a pint or two of dregs, no issues. Only works if you don’t move the keg, but it works.

Yeah, it’s a tradeoff. Less worry about oxygen sucked onto the beer’s surface, more yeast. I’ll say having spunded several beers, the amount of yeast is much less than spunding.