Is this Phosphorous deficiency?

Green-O-Matic autoflower greenhouse seeds, half way through week 7, 3 gallon smart pot, ffhf soil, general hydroponics nutrients, cheap 1000w led 2 cfl 75w, started about a week ago thought it was nutrient burn think it might be phosphorous deficiency.

i dont think its either i think its just the natural color. plant is maturing. might be a little hungry how much you feeding?

I feed 3/4 of a gallon every two-three days ppm never above 600 ph varies from 6.4-6.8