LECA
December 22, 2007
Expanded clay pellets, most commonly known under the brand name LECA (acronym of light expanded clay aggregate), also known as Hydroton and under the non-proprietary terms fired clay pebble, grow rocks, expanded clay (pellets) or hydrocorns, are small globes of burnt and puffed clay, used in construction and farming, and there especially in hydroponics.
They are available in different sizes such as 4/8 (”4 to 8 mm in diameter”), 8/16, 10/20, 1/4 or 2/4. The dry density of lightweight expanded clay aggregates is 300 to 500 kg/m3.
Originally a Danish innovation, LECA is now manufactured in Algeria, Argentina, Austria, Belgium, China, Denmark, Egypt, Finland, Iran, Italy, Norway, Portugal and Sweden.
Farming
Expanded clay pellets are anorganic, have a neutral pH, and transport and store water. The gaps between the kernels provide a good aeration (oxygen transport) of the roots.
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.
[...] with nutrient solution. A variety of materials can be used for the medium: vermiculite, perlite, clay granules, rockwool, or gravel. This method requires little maintenance, requiring only occasional refilling [...]