Hey there, bro! 👋 Your girl is experiencing a slight phosphorus deficiency (red or purple stems on the leaves). The phosphorus deficiency is likely caused by an excess of nitrogen, but you're at the early stage of deficiency and it's not dangerous, though you should take action! Feed your girl in a ratio of 1:3 (grow:bloom). The "grow" nutrient has a lot of nitrogen, so lower it, and the "bloom" nutrient has a lot of phosphorus, so increase it. By the middle of flowering, stop using the grow nutrient and only use the bloom nutrient! 👌😇👍 Good luck, bro!