LECA (clay pebbles)
Also known as: Hydroton, Expanded clay, Light expanded clay aggregate, Clay pebbles, Grow rocks
Preferred
Properties
| Bacterial surface area | 250 m² per m³ |
|---|---|
| pH effect | neutral |
| Weight class | very light |
| Longevity | 10 years before degradation |
| Cost tier | moderate |
In a system
- Lightest of the common biofilter media at roughly 300 kg/m³ flooded, so bed structure (timber, IBC tote, fiberglass) doesn't need to be reinforced
- Round pebbles with rough internal porosity give about 250 m²/m³ of bacterial surface area, enough for typical hobby fish loads
- Floats when dry, so beds need to be flooded slowly the first time or weighted; once saturated it stays put
- Reusable indefinitely with a hot water rinse between cycles; no measurable degradation across 10+ years of continuous use
- Drains and re-floods cleanly in ebb-and-flow beds because the round shape and uniform 8-16 mm size doesn't pack tightly
Notes
Rinse new pebbles thoroughly before use; the manufacturing dust clouds water for days otherwise. Cheaper hydroponics-grade brands work as well as the premium ones; the manufacturing process is the same.
Sources
uvi-aquaponics-program, wilson-lennard-aquaponics-handbook, manufacturer-spec-sheets
See the full aquaponics media reference for comparison, or use the aquaponics system designer to plan a complete setup.