Cannabis is a hyper/dynamic accumulator.
The organic method relies on the "passive ionic uptake" pathway for nutrient absorption. Cannabis enjoys additional pathways of uptake, which tend to draw in unwanted and unconvertible elements. These actions makes it a great plant for "phytoremediation" which is the process of using plants to pull toxins out of soil.
These unwanted and completely un-necessary elements absorbed by cannabis will not flush or fade out. Period. They are fixed to new plant tissue and will be present at harvest day and beyond.
Your goal is to provide a nutrient availability which does not exceed what the plant needs. Cannabis can and will absorb what it doesn't need, so keep it out of the root zone.