hey there Dave, you're right about magnesium issues, the thing is it will take more than a few days to recover. Right now you're on a heavy light cycle, so that's why the plant needs more Mg , since giving more Mg doesnt help, that means the plant needs more than it can absorb, so what you need to do is reduce your light cycle by a few hours, maybe try 14/10. hope this helps ! 🚀