VitaLink Clay Pebbles are 8-20mm clay pellets that have a lower bulk density meaning they are lighter which leads to higher porosity and therefore more water retention. These pebbles offer a tumbled surface without sharp edges that can cut delicate roots and harm plants making them vulnerable to pests and diseases. They ensure good aeration (non-compaction) and are extremely stable in both pH and EC and help prevent excess acidity build up. The VitaLink Clay Pebbles perform excellently in Flood and Drain systems where oxygen exchange in thick root mass is essential. Their strong structural integrity means that they are less likely to break and compact which can cause blocked dripper systems. These clay pebbles are pre-washed to aid in stability. The pebbles drain freely and do not hold any excessive water and this is why they provide good oxygen levels around the root and why they are well suited for Flood and Drain systems. They are also used extensively for Multi pot systems and drip fed WaterFarm type systems.