I use liquid karma in my grows and the roots always have an off white color to them. I have also had root disease. The roots get really brown and stop growing showing none of the fuzziness your roots show. After looking at the picture the lighting may be somewhat different on the roots in the back of the tub.

As far as nutrients go you didn't mention what the ppm was. The stage your plants are in I usually try to keep the ppm to about 300-400. You can always go up, but it may be too late to go down when there is too much. Why cut off their nitrogen when that is what they want in veg stage?

Also, can you give me some info on that white pvc manifold with sprayers. I like that setup.