Turtle's got your PPM question. The roots can be discolored from the nutes, They are about that color when you mix them aren't they? Kind of spooked me when I changed to GH 3 part. My orange bud roots look almost like those and I have no problems. 68 degrees is perfect for oxy amounts in the water. You are close at 72. I wish I could get the co2 running also. Remember clones are as old as mother, some times they will look a little strange but should straighten out.