Expanded clay aggregate (exclay)

Heated clay-pellets also known under the trademark “Hydroton” or “Hydrokorrels”, or as LECA (light expanded clay aggregate), are suitable for hydroponic systems, where all nutrients are carefully regulated in aqueous solutions.



The clay is formed into round pellets and burnt in rotary furnaces at 1200 °C (2190 °F). Thereby the clay expands like popcorn and becomes porous. This substrate is very light and thickens gradually. Depending on the burning and production process, the uniformity of the pellets can be discontinuous due to irregularities in the form of individual pellets. Due to its characteristic to be able to be cleaned and sterilized - that usually happens by washing them out in white wine vinegar solution, chlorine bleach or hydrogen peroxide (H2O2); afterwards a complete elution follows – manufacturers estimate, that LECA is a sustainable and reusable growing medium.

A less widely spread point of view says, that due to the possibility that the root development gets in the medium, the clay aggregate shouldn’t be reused – even if it is cleaned before.