On the off-chance that you might have inadvertently introduced lacto during transfer, do you mill your grain in close proximity to your fermenters?
Also, can you document your steps when transferring from primary to the bottling bucket just in case something stands out? Be as specific and detailed as possible.
No, I don't mill grain near my fermenters.
Primary to bottling procedure:
-Move primary (airlock still attached) from basement to kitchen counter. Let sit about an hour (I usually wrap a clean towel around it to keep sun out).
-Put autosiphon, spigot (which was brand new this time - but I put the spigot, washers, and nut in the sanitizer bucket separately), and tubing in sanitizer bucket full of Star San. Run sanitizer through autosiphon, tubing, and spigot.
-Let that sit for 2 minutes.
-Dump some of sanitizer in bottling bucket, shake it around (obviously it spills out since there is a hole in bucket for spigot).
-Attach spigot. Dump most of sanitizer in bottlling bucket (leaving autosiphon and tubing in sanitizing bucket with some sanitizer). Let sit for about 5 minutes. Drain some sanitizer through spigot. Close spigot. Dump out rest of sanitizer.
-Take airlock out of fermenter. Put autosiphon in fermenter. Attach tubing. Put tubing in bottling bucket. This last time I then put sanitized plastic wrap on the top of the bottling bucket, taking care to cover it completely. Before that, I used a lid (both ways, yielding infected beer)
-Dump in sugar / water which was boiled for five minutes.
-Start autosiphon.
-While that is going, sanitize clean bottles in star san for 2 minutes per batch. Caps are also sanitized in star san for 2 minutes. Bottling wand also goes in there, taken apart.
-Spray spigot with spray bottle of star san. Attach tubing and bottling wand to spigot. Fill bottles. I place caps on bottles as I go along, then actually cap them after they are all filled.