Nitrogen Deficiencies
Plants will exhibit lack of vigor, slow growth and will be weak and stunted. Quality and yield will be significantly reduced. Older leaves become yellow (chlorotic) from lack of chlorophyll. Deficient plants will exhibit uniform light green to yellow on older leaves, these leaves may die and drop. Leaf margins will not curled up noticeably. Chlorosis will eventually spread throughout the plant. Stems, petioles and lower leaf surfaces may turn purple.
This sounds exactly like what is happening to my plants to a T, but the extra nitrogen didn't do anything. It said that Nitrogen is best absorbed with a pH between 5.0-7.0 and I am 100% sure mine has been within that range.

WTF???:wtf: