Hydro Clay Pebbles (Leca) Orchid/Hydroponic Grow Media - 10 lbs. (More than 10 Liters) by PowerGrow Systems Perfect as a Hydroponic, Aquaponic, or general growing medium pH Neutral and inert and certified for Agricultural use Also great for Orchids and decoration Clay Pebbles provides excellent aeration and water retention Once of the time tested and most widely used growing medium.