This looks like a really bad case of P defiency. A diary would really help if you care to start one would be so much easier and accurate with a recorded history or the answers will only be generated on it being your 7th grow. Best of luck
Clear interveinal stripes on the leaves. Purpling everywhere = Magnesium chlorosis from too intense light.
This is a photoinhibition, light energy is exceeding the photosynthetic capacity of the plant.