Purple/blue leaves?

I have a White Widow that's about 10 days old.What is causing the blue/purple leaves and stem?Is it good or bad?Could the fan blowing on the plants cause the blue/purple leaves?I'm growing them in light warrior soil.I water them every other day or so with 6.5 ph water.The temps are 65-75.Humidity is 42%.The cool tube 600w MH is 13 inches above the plants.Im running the light at 75%.Is this to much light or to little?And the light schedual is 18/6.Last question.Should i have the plants in a humitity dome at this stage?Thanks!!!!!!!!!

Give it a week or so. I've had that with seedlings amd it usually goes away. Well I haven't had any were it stayed. Just my thoughts.

usually the difference between the lights on and off temps that cause the colour change its probably getting a bit cold on the , nothing to worry about. wouldnt worry about the dome they only need the humidity when there seeds.

not a bad little set up you got there.