Washed yeast pitch gone bad. Please observe a moment of silence for the 24 lbs. of malt and 10 oz. of beautiful Centennial whole hops lost in this tragedy, my second contaminated batch in 11 yrs. and over 300 batches. Crap.
Sympathy. Sounds like you did everything right but got ambushed by some wild yeast.
How old/clean are your hoses? Lots of ugly critters love to live in dirty hoses, and it can be very tough to get them clean, especially if they're old, cracked or scratched. It's cheap insurance to replace your hoses every 6-12 months, or whenever they start looking dirty.