Expanded clay aggregate is a porous substrate for hydroponics (suitable for recirculation). It comprises forming aggregated clay balls 8 to 16 mm. The internal structure is porous, water absorbing and releases nutrients according to the needs of the plant. It's clean, it does not rot and it is free of diseases and parasites. The arlita has a stabilized pH between 5.5 and 6.5, making it an excellent support for hydroponics. It can also be mixed with other substrates. The expanded clay does not absorb water for a long time. Dip the "clay" or expanded clay balls in the nutrient solution 24 hours before transplantation to stabilize the pH.