I think it looks great no problem that I can tell from the pictures, I think that the new growth is normally a lighter shade of green at first just keep watching and waiting dont react on a whim. Keep up the good work
Okay; I don't feel like I have enough coco coir experience/knowledge to say definitively what could be causing the yellowing tips, so I will have to defer to other forum members. They do look really good, though, with just a slight tip issue.