The only issue I see is a little excess in nutrients. The leaves are dark and the leaf tips are burned a little from nutrients. Purple stems are pretty common is a lot is strains, especially since you are growing a dark strain there is nothing to worry about on that. In soil it is easy to overload it with nutrients so it is best to feed them every third watering. Water, water, feed, repeat. Overall your plants look pretty healthy. Good luck finishing them up!