Could also be too much light.
Every time you water do you add nutrients? I see some small tip burn here and there
You could measure the runoff next watering. If you measure the ppm of the runoff you get a slightly better idea of the situation. If the ppm is like 3000 flush that shit out, if its under 800 you can add more nutrients.
ph can be between 5-7, under and above could cause problems.
GL!