This is Why Clean Cannabis is so Rare
Growers are not aware that cannabis is a Dynamic Accumulator. Cannabis absorbs both needed and unneeded elements from the root zone.
Use Pharmaceutical Grade Nutrients
Pharmaceutical grade nutrients are 99.9% contaminate/heavy-metal free. I refer to lower grades of nutrients (agricultural and horticultural grade) as HOBBY nutrients, excellent for growing beautiful vegetables and ornamental plants.
Hobby nutrients should not be used for growing cannabis.
I'm Teaching Clean Hydroponic Growing for Cannabis
Looking to learn clean cannabis growing? Check out #tcghydro where I'm posting what I've discovered the last 15+ years.