Check the listing for details. Hydrofarm GROW!T (#GMC40L) Clay Pebbles (4mm-16mm) 14 Liter Bag. Condition: New. Listed at 50.70 USD. Hydrofarm GROW!T (#GMC40L) Clay Pebbles (4mm-16mm) 14 Liter Bag PRODUCT DESCRIPTION Hydroponics users have found out that clay pebbles are an excellent way to increase their yields! Extremely stable in both pH and ECMade from 100% natural clay, ideal to mix into coco coir or soil to aid aerationStrong structural integrity, they are less likely to break and compact, which helps to prevent dripper systems from getting blockedUse in hydroponic growing, they are ideal for flood and drain, deep water culture and drip feed systemsDrains freely and does not hold any excess water, providing good oxygen levels around the root; suitable for flood and drain systems, multi-pot and drip feed systems and are also ideal in aquaponic systemsLooks great as a top dressing for pots and also helps to prevent evaporation GROW!T horticultural clay pebbles are made from 100% natural clay. They are clean, pH stable, and offer great aeration and drainage in hydroponics, especially in flood and drain, deep water culture, and drip feed systems. Due to their unique structure and ability to cover a large surface area, they offer the ideal environment to foster beneficial bacterial growth around the root zone, leading to naturally healthier plants.