What is wrong with my purplematic cbd?

This is a classic case of phosphorus deficiency... Phosphorus cannot be absorbed by the plant unless the pH is in the proper range and yours was not... you need to maintain it between 6.2 and 6.5 assuming you are growing in soil - if you're growing in hydro, that range should be 5.5 to 6.2. The little brown spots on the leaves are also a calcium deficiency which, again, was caused by your pH. There are other causes but this is the most typical... there are also a number of things you need to do - read this article about it and decide, based on what you've been doing/are doing, which of the remedies you need to do.. https://www.growweedeasy.com/cannabis-plant-problems/phosphorus-deficiency Good luck!