1ml x3 on a 45p sounds like a lot. 0.5-0.75ml of iron also sounds like a lot.
The excess metals probably adsorbed onto the high CEC substrate so even after not dosing, the substrate will still provide plants with them. If the metals are imbalanced or excessive, then the substrate could be considered toxic. This is one of the problems with excessive dosing of an unbalanced trace metal nutrient fertilizer.
My substrate, Floramax (also high CEC), became toxic as a result of excessive CSM+B dosing. I'm now doing various substrate tests to confirm and on how to remove the metals from the substrate.