Lava rock (scoria)
Also known as: Volcanic rock, Scoria, Pumice rock
Preferred
Properties
| Bacterial surface area | 400 m² per m³ |
|---|---|
| pH effect | alkaline at first, washes off |
| Weight class | medium |
| Longevity | indefinite |
| Cost tier | low |
In a system
- Highest bacterial surface area of any common media at 350-450 m²/m³ thanks to the natural vesicular porosity
- Roughly 800-1000 kg/m³ flooded, three times the weight of LECA, so bed framing needs to be sized for it
- Releases calcium and magnesium during the first 2-4 weeks of operation and bumps pH 0.3-0.5; cycle the system before adding fish
- Sharp edges can cut hands; gloves recommended during installation
- Cheapest option in volcanic regions (US Pacific Northwest, Iceland, New Zealand, Italy) where it's sold as garden mulch; expensive elsewhere because of shipping weight
Notes
Source from a landscape supplier in 19-25 mm grade; aquarium-grade lava is the same material at five times the price. Avoid dyed lava rock used in barbecues; the dye is food-grade but the rock fragments are inconsistent.
Sources
uvi-aquaponics-program, wilson-lennard-aquaponics-handbook
See the full aquaponics media reference for comparison, or use the aquaponics system designer to plan a complete setup.