coco grow.... pale leaves?

hi all, im just trying out my first grow in coco coir and everything seems to be going fine except im just slightly worried about the paleness of some of the leaves.
they seem healthy and growing well, just this small problem.
all im using at the moment is just a mild ionic coco feed of about 1.5ml per liter, the ph is fine about 6, so is the run off. was thinking its maybe just N shortage and will be fine after the initial stretch??
any tips/advice from coco growers would be most appreciated, thanks

i would say lack of nitrogen.

use more nutes, they are hungry

or maybe heat stress??