I agree, your pH is too low for a coco grow. 5.8-6.2 is good for coco. also, your P and K is too high. your N is too low.

Before adjusting nutes, adjust pH first. see if the problem corrects itself.
the purple stems and yellow leaves show signs of N deficiency, but your leaves are also showing signs of nute burn.

pH first, then nute adjustment.