Expanded Clay Aggregate (ECA) is commonly used in the world of hydroponics and aquaponics. The large pore space of ECA ensures proper water flow with no clogs or blockages, and it has the capacity to hold plenty of air bubbles, which helps keep the root zones of most plants aerated and oxygenated.
It’s also very affordable and can be reused over and over, with no need to discard the material. And because it’s a loose growing medium, compared to crushed granite or pea gravel, it’s easy to harvest plants, which can save large-scale hydroponics and aquaponics producers quite a bit of time. It’s appropriate both for media bed and Dutch bucket techniques alike.