[brulosopher]

It was bound to happen. After nearly 18 months and over 40 successful tests since starting the xBmt series, I screwed up. Rather than sweeping it under the rug and pretending it never happened, I decided to share the story of how I lost 10 gallons of beer.

http://brulosophy.com/2015/09/03/an-exbeeriment-failed-or-how-i-lost-10-gallons-of-beer/

[AmandaK]

Happens to the best of us. Glad it was an easily identifiable source!

[chumley]

Seven pitches is pushing it.  I have done up to 5 with lager yeasts, and the fifth ferment definitely had some non-lager character with it.  Three is about the most I would do with ale yeasts.

[brewinhard]

Aww man, that sucks!  Like Amanda said, at least you know the source of infection. 

[ynotbrusum]

I have no problems with repitching Lagers for some reason, but the two contaminated batches I have ever had were ales - one due to double batching and using Iodophor on both despite sitting in the sun between batches.  The other was from a dry yeast that mutated slightly, I believe.

Keep up the good work, Marshall.  You are advancing the Homebrew knowledge base incredibly well.

[toby]

I strongly empathize considering my own recent issue with a couple of stored yeast samples.  The main difference is that I'm uber paranoid about it at the moment, since this was a relatively rare case for me.  I had isolated and stepped up some WLP028 and WY1728 collections since I've been brewing more Scots ales this year.  Well, when I brewed my BrewUnited Scotch Ale, I figured I'd make a 1L starter out of two of my small jars (since it's a really big beer).  I was nonplussed when the first jar I pulled had this thick crud at the top.  Apparently I had picked up a contamination in two jars since pulling another two turned up one with a slight film (I'd describe it as a starter pellicle).  I took a closer look at all the other jars, and only those two seemed to have issues, so they're going to get a special treatment.  But, my philosophy is to trust your senses and not assume.  I visually and olfactorily (not even sure if that's a word, but I'm going with it) checked all the rest before settling on the 2 I used.  Only the WLP ones had the issue curiously.  These were only 2nd generation, though, so I'm assuming more an isolated issue with those 2 jars (out of 10 or so).

[brewinhard]

Most recently I have stopped storing yeast for more than 2-4 wks.  If I know I won't be using it again in that time frame, then I simply don't even bother saving it.  I have more peace of mind starting from a fresh pack.