Novato con manchas en hojas DWC

I would say you either have your light too close and/or excessive heat, or you have lockout from bad ph or something maybe. Could be lack of cal mag as well as you suspect, but if your adding it in proper doses you shouldn’t see that. I would check your ph pen calibration, cycle out your old water with fresh water/nutrients at half recommended nutrients dose and proper ph(after you confirm ph calibration). Then if you can get a light meter app or an actual meter and find your sweet spot for you canopy so you know you are not over/under doing it for light, takes the guessing out and maximize your yields and helps keep stretching down too. Last if you can, get a cheap laser temperature gun so you can measure your actual canopy temperature will really help you dial it in. Hope this helps, cheers 💨