Classic iron lockout.
I don't know diddly about the SuperVit or Hesi line. But what is the pH of the nutrient solution before you pour it through the plant? Your tap water pH is very low, and don't bother with the Brita filter.
Water at pH 6.8-7.
Runoff should never be above pH 6.9. 7.5 is way too high.
I would hit those with a light foliar spray of Spray n Grow or Iron Green to correct the lockout (spray n grow is preferable to buy since it helps many deficiencies). Then correct your feeding/watering pH.
Is the soil the BioCanna bagged medium, or is it a different one? I'd actually switch to a Canna nute for simplicity, preferably the Canna Bio if you want to run the complete system as intended.
Also- what is your pot volume, and how tall are the plants?