Also known as Hydroton are small globes of burnt and puffed clay, used in construction and farming, and especially in hydroponics. A clean and attractive soil free media with many applications in hydroponics and containers. Leca is completely inert, pH neutral and reusable. Derived from a renewable and plentiful source (clay), Hydroton is considered an ecologically sustainable growing medium. The clay is formed into pellets and fired in rotary kilns at 1200°C. This causes the clay to expand, like popcorn, and become porous. Hydroton hydroponic growing media is light in weight, does not compact and is completely reusable - it can be cleaned and sterilised after use. They are also inert, pH neutral and do not contain any nutrients. The pellets drain freely and do not hold any excessive water, which is why they provide good oxygen levels around the root and why they are particularly suitable for flood and drain systems.