pic 1 looks like Phosphorus def.
Phosphorus (P) deficiency during vegetative growth. Many people mistaken this for a fungus, but look for the damage to occur near the end of leave, and leaves the color dull grayish with a very brittle texture.
pic 2 looks like Magnesium def.
Magnesium (Mg) deficiency.
Magnesium deficiency will exhibit a yellowing (which may turn brown) and interveinal chlorosis beginning in the older leaves. The older leaves will be the first to develop interveinal chlorosis. Starting at leaf margin or tip and progressing inward between the veins. Notice how the veins remain somewhat green
pic 3 might develop the same.
whats your pH at?? it can just be a lockout