Some type of of deficiencies white spots on leaves

I'm growing in pro mix hp+. When I feed and water I ph to the low sixes 6.3-6.5

then you my friend, have stumped me

whats the rh and air movement in your tent? may be starting to get a few burn spots from the plants transpiring too much. whats the texture of the leaves? do they feel nice and soft? or are they starting to get a dry, rough feeling to them?

I just re calibrated my ph pen so I'm thinking that may have been the issue...

can't hurt, see what they look like next week after a week of the proper ph range