I decided to try selenium toning before fixing my POP. I rinsed the image for longer than necessary to make sure I washed off any thing still there. I put it in the 3%ish selenium solution for 3 minutes with constant agitation. When I took the image out of the selenium it was perfectly clear. I then went through the two fixing stages. By the time my last fix was done the selenium solution had turned a light Tea color, and it has continued to darken. Now we are looking at Earl Grey. What caused this?