Clay pebbles, or LECA (lightweight expanded clay aggregate), are small balls of clay fired in a kiln so they expand and become porous. They are pH-neutral once rinsed, hold almost no nutrients and only a little water inside their pores, and leave large air gaps between the balls. That makes them a classic support medium for hydroponic systems.
In practice
Clay pebbles fill net pots in DWC and RDWC, fill trays in ebb and flow, and line the base of containers. Rinse new pebbles well to remove dust that can clog pumps, and soak them before use. Because they dry quickly, plants grown purely in clay need frequent irrigation or roots that reach the solution. They can be washed, sterilised and reused for many cycles.
Don't confuse with
- Perlite: much lighter and finer; usually mixed into a medium rather than used alone.
- Pumice: natural volcanic rock with a similar role; irregular shape.
A net pot is a plastic cup with slotted or mesh walls that holds a plant and its medium in a hydroponic lid, letting roots grow through into solution.DWC (deep water culture) suspends a plant's roots in an aerated nutrient solution, typically in a bucket with a net pot lid and an air stone.RDWC (recirculating deep water culture) links several aerated buckets to a central control reservoir, pumping solution through all of them to keep conditions uniform.Ebb and flow (flood and drain) periodically floods a tray of potted plants with nutrient solution, then drains it back to a reservoir, pulling fresh air into the medium.Perlite is a light, white, puffed volcanic glass added to growing mixes to increase drainage and air space; it is chemically inert and holds no nutrients.A growing medium (plural media) is the material roots grow in, such as soil, coco, rockwool or clay pebbles, which anchors the plant and holds water, air and sometimes nutrients.Hydroponics is growing plants without soil, feeding roots a complete mineral nutrient solution either directly in water or through an inert medium.
