Brown leaf tips

I’m growing Bruce Banner auto hydroponically. Two plants that are about 10 days apart timewise. The older plant is in week five and is 24” tall. Getting 18 hours of light 18” above plant top. 1000watt led light. pH is 6.2, TDS1400ppm. Her leaf tips are turning brown and have a slight bit of curl at the very tip.

should I be concerned?