Diagnosis help pls

Hi there SnowGoon, i might have thought that was just the consequence of water / feed splashing on your plant then getting dried by the lights. But now i'm thinking it's the start of Mg deficiency. Often times with such intense light schedules you will cause the plant to need more Mg than it can possibly absorb fast enough. That's why you're seeing this although you're adding calmag. If you can / want try reducing your light schedule to reduce the light stress which is the root cause. Otherwise you can try a calmag spray. After all absorption through the leafs is much more efficient than through the roots. Just spray at sun up twice a week and hope it stops the problem. Hope this helps ! 🚀