please help

this is my first time under lights growing in coco soil and vermiculite mix I'm just wondering why my leaves are discolored around edges I'm pretty sure it could be a magnesium deficiency just no sure I'm also using a 400w hps cooltube and a large 300w cfl dual spectrum to add a bit of blue spectrum what do you guys think ?? I also use all seasol products seasol heath treatment seasol powerfeed and seasol veggies extra fish emulsion

And what's the best way to fix this problem

It could be a mag issue, try giving it some epsom salts.

If they are in coco and verm, how often do they dry out?

They dry out probly every 3 days and how should I apply Epsom salt