no thats not normal, they should be completely white, when they get really big they start to yellow a little and get a harder texture to them. what are your water temps like? i guess it also depends on nutrients.. some of them will stain the roots, but that looks like you got some junk in your bucket turning them dark up higher.
it seems that my grow nutes and bloom nutes have sortove setteled leaving miniture specks in the water is this what is causeing the problem to over nute and my roots being like this?
roots should be , white, pink, also roots take the color of the nutrients solutions. but dark brown is not normal.
my temps arent high at all the water is cool to the touch 65-73F Edit: and if it was root rot wouldnt my plant not grow and the ph start droping?