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: high porous surface area colonized by nitrifying bacteria, reduces or eliminates need for a separate biofilter
Light enough that a 4x8ft media bed remains movable when dry
Inert: does not buffer pH; system pH will drift toward source water natural value
Floats when first wet; pre-soak for 24 hours before stocking plants or it will displace water from the bed
Cheap-grade products release clay dust on first fill; rinse aggressively until 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

Standard hydroponics/aquaponics workhorse media for any system where pebbles are appropriate. Reusable for years; rinse between crops to remove root debris. Sterilize between sick-plant cycles with a bleach soak (1:9 bleach:water) followed by triple rinse and re-pH.

Crops that work in expanded clay pebbles

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

Sources

Data drawn from: aquaponics-association, manufacturer-spec-sheets. Last verified 2026-05-13.

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