Yellowing leaves

Its nitrogen defiancy my friend. Thats clear from it starting at the lower leaves the grower is right she does not need much nitrogen at this stage but nitrogen is a mobile nutrient within the plant meaning that no matter what stage she is in she will require some form of nitrogen to stay healthy other wise she will eat her fans for it like she has done here im not trying to argue with the other grower I respect his answer its not wrong per say but yeah mobile nutrients being NPK plus cal mag are always in use by the plant but are needed in different concentrations at different stages this is what feed tables are for :) I would advise looking into the nutrients brand you have grab their feed table and follow that as a base line. Though the best thing is one dose of nitrogen should be enough to solve this :)