Expanded clay pebbles

Also known as: LECA, Hydroton, Clay balls, Expanded clay aggregate, ECA

Properties

pH effect	neutral / inert
Water retention	low
Drainage	excellent
Oxygen to roots	high
Bacterial surface area	high
Reusability	high (many cycles)
Cost tier	moderate
Weight	light

How it affects the system

Excellent biofiltration substrate for aquaponics: the highly porous surface (total porosity up to about 80%) is colonized by nitrifying bacteria, reducing or eliminating the need for a separate biofilter
Light enough that a 4x8 ft media bed stays movable when dry
Inert and pH-neutral (around pH 7): it does not buffer pH, so system pH drifts toward the source water's natural value
Floats when first added dry, so pre-soak for about 24 hours before stocking plants or it will displace water from the bed
Cheap-grade product releases clay dust on the first fill; rinse aggressively until the water runs clear

System compatibility

Works well in:

media bed (ebb and flow)
drip
wicking bed

Avoid in:

NFT channels
deep water culture (rafts)

Care notes

A standard hydroponics and aquaponics workhorse medium for any system where pebbles suit. It is reusable for years; rinse between crops to clear root debris, and sterilize between sick-plant cycles with a bleach soak (1:9 bleach to water) followed by a triple rinse and re-pH. The pellets are fired in rotary kilns at around 1,200 C, which expands the clay like popcorn into light, porous, roughly round aggregate that resists compaction.

Crops that work in expanded clay pebbles

122 edible crops in the catalog list this medium as compatible.

Back to growing media reference

Properties

How it affects the system

System compatibility

Care notes

Crops that work in expanded clay pebbles

Further reading