1) the plant will produce acids that will drop the ph , especially in weeks 3-6
2) the plant will eat nutrients dropping the ppm/EC , and drink water for transpiration
3) pull the big fan leaves to get more light to bud sites,
4) is there a fan in the room /tent ?
5) dont worry about pulling off leaves , but always leave at least one inch of stalk , stops bud rot into plants
6) purple stems is more often a genetic factor than a nutrient issue , but can also be caused by cold nights .
7) don't worry 😉