Foamed clay was invented in the early 20. century in the USA. From there it found it's way to Europe and Germany only very slowly.
Foamed clay is light in weight and - due to it's consistence -  allows water to run through almost unhindered. At the same time the large surface of the foamed clay bubbles can hold back nutrients and ions out of the water. So, foamed clay works similar to a retard medicine. This effect supports the plant in generating roots.

Blusana expanded clay balls, for hydroponics, 5 litre Art.Nr: P6532 EAN: 4004256270077 Expanded clay balls are indispensable in hydroponics. The Blusana expanded clay balls offer the right base for your plants. 5,50 EUR incl. 19 % Tax excl. Shipping costs   Expanded clay balls, 50 litres Art.Nr: 050140 EAN: 4024102133172 Expanded clay pellets are used as a substrate in hydroculture / hydroponics, or as a soil additive. They can also be spread as a top layer over soil around plants to prevent the growth of unwanted weeds. from 13,50 EUR Price per Unit: 14,50 EUR incl. 19 % Tax excl. Shipping costs