A friend of mine and i have been working on a very close situation to yours. He kept saying his prints would turn pink by the time they finished washing. He thought it was his developer or fixer or something like that. But when I asked him how he set it up I didn't think it was the chemicals. I took some of the so called pink prints and rewashed some at my darkroom, then refixed some. nothing happened. then I throw one into Potassium Ferricyanide and found that the print turned brown! Well what he thought was pink was a very light brown stain. He uses well water at his home so we tried something different. Instead of washing his prints for 30mins. we did what perma wash indicatd for SW paper. 5 mins wash 5 mins perma wash and then 5 mins wash. NO STAINING. There is something in his water that is reacting with the silver in the print and staining it. He is going to get his water checked for metals and elements to see if we can figure out which one.
I'm not sure this is your problems but, I thought I would relay what we had.

Regards

Michael Andersen