dwc roots colour changed

All that is completely normal man. Nothing to worry about. I'm moving into DWC. And even the roots in my coco were white first when they grew thru my air pot and now they are like a rusty brown. Dif nutes, espically the dark coloured 1s will dye your roots. They looks really healthy you'd know if they weren't you would see massive signs of stress and all sorts of nute uptake issues. Just keep that in mind if she's healthy on top she's healthy below. Happy growing, good luck.