What do the plants actually grow in?
This is really interesting. The plant roots are actually flowing in a river of nutrient rich water in our grow beds in the aquaponic farms. When we first plant the seeds, we place the seeds in a rockwool cube to support the sprout and seedling as it is getting established. Once we move the seedling in the rockwool cube from the germinating rack to the grow beds on the farms, we place the rock wool cube in a reusable plastic net pot that holds the rockwool and seedling afloat on the foam rafts floating on top of the water in the grow beds. Since a picture is worth a thousand words, you can see this in the photo below.