Growing medicinal cannabis for the "hemp oil" is there any worry that heavy metals chemicals or toxins are released when consuming the oils?
I think like w/ any fertilizer you'd want to perform a good flush before harvest to ensure any icky flavors go away. Most people just run clean water for a week or two before harvest. I use the GH line, w/ the lucas formula and it works great and I haven't had any adverse effects.
I second that, been using gh nutes and the lucas formula for years in my drip totes and couldn't be happier. Flush for a week or two and there shouldn't be any heavy metal problems.