Not sure what you were saying..that's one long sentence! I'm not here looking for help, i come to this section only to help others, and no, when i clicked on the thread, i didnt see the date of OP until i saw your post. I was simply telling you not to put much thought into the fact that light stress is causing purple stems/petioles. I said Labs Dexter said it best in the last post. Also was reminding you, that if you do have too much light for a plant, it will not be fixed by adding cal-mag..too much light, is too much light, nutrients don't balance out light stress. Added CO2 however, can help higher light, within limits.