One other thought for nutes/ph vs lighting......he said the plants were growing great guns....VERY common with nute burn since the line from one to the other is not too far. One minute they ARE growing great....then they are burned.

With lighting I don't think they would be that green and growing that well.....the heat of the light would have caused bleaching etc....

These are my thoughts. Good Luck.....I really do mean that.