I've been thinking of cutting costs on feed. Currently I'm taking care of a coop of 23 chickens. They eat about 50 pounds a week, or $19. But I heard duckweed is healthy and can replace about 25% of their feed. However, I have also heard there might be contaminants such as heavy metals in duckweed. There is a recycled wastewater pond on the campus, covered in duckweed. So I thought, cool! free food! But might it have heavy metals in it? Is there any way to know, like chemical testing?