Ton Kiesel

Clay pebbles – expanded clay, hydroton, LECA – are fired clay balls with a hard shell and a porous middle. They hold almost no water, so the root zone is mostly air, which is exactly what a recirculating hydroponic system needs.

What they are used for

• Flood and drain. The classic pebble medium – floods and drains cleanly with no waterlogging. See flood and drain systems.
• DWC and bubblers. Used in net pots to support the plant while roots hang into the solution. See DWC systems.
• Dripper systems. Fast drainage suits little-and-often feeding.
• As a top layer. A few centimetres over soil or coco slows evaporation and deters fungus gnats laying in the surface.

Why growers like them

They are inert and pH neutral, reusable almost indefinitely, and impossible to overwater. The trade-off is that they hold no reserve at all – if the pump stops, roots dry out within hours. Pebbles are for systems with reliable, frequent irrigation, not for hand watering.

Rinse them first

New pebbles carry clay dust that will clog pumps and drippers. Rinse thoroughly until the water runs clear, and give them a soak at around pH 5.5 before first use. Between crops, wash, sterilise and reuse – they are one of the few media that genuinely last.

What we stock

Expanded clay pebbles in grower and bulk bags. Compare with perlite and rockwool, or see everything on growing media.

Why buy clay pebbles from The Hydro Bros?

We are a hydroponics shop in Croydon and we build these systems for customers, so we can tell you how many bags a given system actually takes. Discreet UK and European delivery, and excellent customer reviews on Trustpilot.