Problem with my young friends

[Pajeh]

hey guys im new here, this is my first post and also first time grower… i have 3 little friends friend in here that i dont know the issue on her.
*400w metal halide lamp 18/6hrs
*24°C-27°C temperature range with lights on
*50-60% humidity range
*strain unknown
*using coconut coir
*about 6-7 weeks old

1First friend

2 Second friend

3 third friend

please help guys, i dont know what to do, i tried npk on the first friend but didnt help… thanks in advance, sorry for any mispelled word.

[MAXHeadRoom]

what nutes are you using? and feed schedule?
What is your ph and ppm going in?
What is your runoff ph and ppm?
What is your light height?

First thing you do when you have a problem in coco is flush with phed water 3 times volume of pot. Then start over with correct ph and ppm level