Couple plants showing severe leaf damage, rest of garden looks great?

[blackg0d]

Using 65-100 gal soil pots outdoors under greenhouses. Decent sun but far from full sun. Supplemental lighting. Empire blend soil (high quality). GH flora series full line of nutes. Feeding every other water. Watering close to every other day. Always checking PH with Hanna Combo pen. Sprayed with flying skull nuke em quite often, but always as directed, in the evening after sun goes down and lights are off. Seeing some extremely burned leaves on a few plants, with almost no warning signs ahead of time, seemingly came out of nowhere. Rest of garden looks very happy. Small chance a tiny bit of water softener salts got into the water, but that part of the system is before we Ph and mix a 265 gal res. So it would be very minute. Highly doubt thats the issue. My only thought is that the soil has an abundance of one nutrient that we are also feeding it, and that nutrient is over abundant in the soil. Any ideas IC?