Hi,
Firstly, your in hydro. So 6.5 is too much. You want around 5.8/5.9. 6.1-7 is for soil growers. A boron deficiency in cannabis is relatively rare unless a plant is underwatered or in a really dry environment, and is usually accompanied by other types of nutrient or pH problems that appear as problems with the leaves.
The first signs of a cannabis boron deficiency is abnormal or thick growth tips along with brown or yellow spotting on new leaves.
In hydro, boron is best absorbed by the roots in the 5.5 – 6.2 pH range (in hydro, it's generally recommended to keep the pH between 5.5 – 6.5, but boron specifically tends to be best absorbed below 6.2).
Any brown spots on the new upper growth is a calcium deficiency. For now I'd back off the feeding until your corrected the issue and only feed it what it needs and you plants are a deep green anyway. I also noticed mild nutrient burn on the tips, so I'd definitely drop the nutrients.