brown roots but no slime

I just changed my Res and I noticed that my roots browned a lot considering no change in plant color. My ppm is 825 and the are 6 plants all beautiful green Ph is around 5.8 and 6.5 also the brown on the other plant is from my light dropping and burning the plant

if you are using a 3 part nutrient micro tends to stain the roots.

I figured that its happened before but went away just didnt want any stress since my auto has started its flowering