Leaves turning purple what is needed

So first my leaves was turning yellow so some suggest it’s was from nutrients deficiency so I gave it nutrients and and bounce back now I’m seeing this

Only a guess but I'm guessing it's nutrient related more specifically I think purpling stems is either due to stress from training or a sign of a Calmag problem.

Calmag problem could be from either not enough or too much of something and you've locked it out.

Here's a link that I think explains a few things.