Royal kush auto in the cantine boyz

Guysss, week 6 and i dont understand wtf is going on😬😂 What do you think about the yellow leafs ? should i cut it or not? The yellowing i think is underfertilization because the ppm is around 500 and the whater ph is arond 6.3-6.5but if you have any suggestion just help 😘 Beside that the plant is still growing the bud also … Ant another week is passed, se yaa the next weeek regaz🙏🙏