I just wanna grow cool weed

Hi everyone, I'm experiencing an issue with my young plant: the leaves are thinning out and showing yellowing, especially on new growth. I’m unsure if this is due to a nutrient imbalance, pH issues, or something else, and would appreciate any guidance. Here’s my setup and recent feed/drain data: Medium: UGro Small Water: Soft, with initial PPM at 77 CalMag Use: Added Feed and Drain Readings: 7.11 Feed: 500 ml, pH 6.0, EC 423 µS/cm, PPM 209 10.11 Feed: 500 ml, pH 5.5, EC 650 µS/cm, PPM 325 (100 PPM from CalMag) 13.11 Feed: 2 L, pH 5.89, EC 1064 µS/cm, PPM 520 13.11 Drain: pH 5.88, EC 610 µS/cm, PPM 304