backflow into fermenter - beer spoilage?

[Doghead]

I use a blow off tube and a old bottle filled with water/starsan instead of an airlock on my fermenters. I just finished cold storage and moved one of the fermenters out of my fermentation chamber but due to the temperature (I guess that's the reason) i had low pressure on it and when I moved it i had some of the water out of the bottle literally shooting up the tube back into the fermenter. The water in there is kinda nasty since I didn't have enough head space and some of the beer flow over into the bottle during fermentation. What are the chances that I contaminated my beer with it? I mean I had starsan in it but I'm not sure about the concentration of it and its been in the bottle for 3 weeks.

 

[mux]

I think your ok. You just have to wait it out.

 

[aiptasia]

Star san can stay very stable for months depending on the mix water you use. The more pH neutral and the lower the total dissolved solids, the longer star san can last as a sanitizer.

I'd say the odds are pretty low that it'll cause issues. Any minor backwash into the beer will be neutralized by the beer itself due to a rise in pH. Star san works by killing microbes with a low pH (acid based) and it harmlessly neutralizes if the pH is raised above a certain point (4.5 if memory serves). So, I wouldn't worry about it harming your yeasts unless you dumped a gallon of it or so into the beer.

 

[postal_penguin]

If the Star-san was still effective you are likely OK. However, if the overflowing beer neutralized the Star-san you probably introduced some wild yeasts and/or bacteria into the beer. Time will tell if anything was introduced or if it can grow in it.