get a plant conditioner like seasol or seaweed concentrate, use it like a multi vitamin for your plant, while its growing, and whenever she gets sick. conditioners like this are filled with organic compounds which the girls go nuts for. and by the pic, id say too much N. lighten the nutes for a week... however, yellowing on the very inside of the new growth is fixed with epsom salt, and if you use soil, consider the switch to a coco medium or at least a mix of coco, perlte or vermiculture. correcting problems in these mediums is much faster, and easier... Good luck