Bubba X pck

I see a calcium deficiency and the rust spots that comes with it, I also think that some of your stems are purplish which is a sign of Magnesium deficiency. I bet on a lack of nutrients as the plant is also have a slight N deficiency that you can spot by the yellowing starting from the bottom. Your 0.8 Ec is responsible for that , you are in coco so you need to reach at least 1.2 to 1.4 at that stage if you want your plant to grow correctly. Don't need to just add more cal mag but add more of everything's 😊✌️🏼