Aurora white tips problem: first hydroponics system

Hy guys, i have two aurora plants in 10 liters hydroponic system. I'm using advan.nutrien. grow A+B and bloom A+B at ph.6.0 to 6.5 and ec.1.4.( i started from 0.8 ). Now, at just 3 and half weeks the new leaves showing white tip (look at photos [attachment=o279369][attachment=o279370][attachment=o279371] ). Do anyone know how can i resolve it?

I think that it is over fertilization but i'm not sure...i changed the water solution, ec now is 0.9 with 10 ml of A e 10 ml of B ...i hope that my plants will not leave me. Help.