Need Help Please

Hello this is my first grow in hydro. I am wondering why my ladies seem to be curling their leaf tips. My feeding program is 650ppm and my ph is 5.6. The nutrients i am currently useing is Advanced nutrients Seni grow Part a+b, super thrive, Vitaboost,Dutchmaster silica. I also use 35% h2o2. I grow in 3"rockwool cubes in 3.5" net pots. They are in a BC Northern Lights Producer gettin light from 2x400watt Hps, 1x125watt CFL. they Get fed 2 times a day for 5 minutes. I do not use co2 because i was told to only use in flowering stage. Any help would be appreciated thanks guys. My temp is 25c at the base of the plant and 29c at the canopy the RH is 35%. The cabinet is in a small room but i leave the door to the room open so it can breath.