what is it ? help please

Hi,i have a problem with the new leaves,have yellow-white in edge's leaves.I use the ph tester ghe with drop,and the color is light green = 7.0 PH and when is drain with nutrient and with just water is yellow=6,5 PH.Is in last week of vegetation (4week) i use just rizhotonic and Bio Vega,1,5ml/L and i raise with 0,5ml.One watering with BioVega one with simple water.

What's the temp in your tent or whatever your enviroment? What kind of lights and how far away you keep them?

19-20, 2 hps 150w hmmm about 50 60 cm

i think is defficience of zinc

Zinc deficiency? I doubt you have any deficiencies. Those dark green leaves look like nitrogen burn. Knock your nutes down a few hundred ppm and she'll do just fine. Enjoy.

I had this issue with a plant and its ok now, just grew out of it. As long as its still healthy and vigorous it will be fine.