lol nirvana seeds are a bit of a crapshoot!
I was thinking you are looking at a lack of K and or Ca...those elements give the plants strength to fight off disease too... spots like that, necrosis, could be caused by a fungus (I'm not sure in your case). what are you using for source water? Are you adding a calcium supplement? I see the slightest hint of a Mg def but that's not causing the spots.