Yellowish stains

[bk_getrich]

Im growing 2 plants in soil with cfls using gh hydro nutrient, one of them is healthy, the other one is very healthy too but i can see less green (abit yellowish) stains on leaves, whats that ? How can i fix it ? I appreciate your help

 

[Potted]

Do u use any cal mag? And if so what’s your ph going in and out?