Now in Piensa en Verde you have the expanded clay balls from the Plagron house, they are made with raw material directly selected from the volcanic rock.
They may be used in admixture with the substrate to provide a medium with greater drainage capacity.
You can also place them on the bottom to prevent moisture from accumulating in the bottom of the pot.
The arlite gets a good relation between the water and the air inside the substrate, being inert and free of pathogenic elements, you have guaranteed a strong root system and resistant to pests.
If you are thinking of changing hydroponic clay bags, you are in the right place.
Now in your reliable grow shop.