Is there anything different about the plants with the symptoms and the plants without? Is it happening most to the parts of the plant that are closest to the lights? I've noticed some plants are a lot more sensitive to light and heat compared to others. Sometimes some plants are fine while others react poorly in the same conditions, especially Indica leaning strains.
When you put your hand where your plants are under the light, does it feel too hot after 30 seconds? If it's too hot for you it's usually too hot for your plants.
The other thing is have you been checking the pH? The pH being too high or too low is the number one reason people see deficiencies.
If you changed their nutrients right before you saw symptoms, that is definitely a likely suspect, too!