Just a lil advice, and my approach to growing. If it's predominatly green, leave her alone. Everytime I used to stress over small little changes I would just cause more damage and stress to my plants. Go outside and look at a tree, or any plant for that matter. You will notice that not every branch or leaf is perfect. Keep your p.h. between 6.2 and 7.0 and let those bitches grow. Purple stems on fan leaves is common.