Yikes !!! Newest leaves ?burnt?

I've had ups and downs with this grow. Mainly leaves drooping then coming back ... today a new first..the newer leaves look burnt on tips.
All numbers are good pH, TDS, temp, RH%, etc. Plants roots partially in the water yesterday... above the water level today.

What do you consider good? Some strains will eat 10x less then others.but somethimes you just get a genetic retard that cant be helped...

pH=5.8-6.1, TDS=900~700, water=69F., RH=65%,, chamber=76-81F.

What type of lighting do you have over that plant, and the distance between the light and the top of your plant ?
Also what feed are you using please

KIND LED X220 (220 W max) set at 75% ~12 inches above canopy. PAR reading ~800 micro mol/square meter / second.
General Hydroponics BOOST 60ml per 5 gallon, GROW 30ml per 5 gallon at water change. RO water Ca/Mg re-mineralized.
H2O2 currently ~50ppm