Hydroton, grow stone, and grow rocks make great growing media for hydroponic systems. Hydroton retains the perfect amount of water, nutrients and air to support plant growth. Hydroton is made mostly in Germany in gigantic rolling kilns. These tiny little clay balls work great for plant growth. Hydroton has excellent water retention and due to their shape water drains quickly away. Hydroton is reusable! Just wash in a white vinegar solution or hydrogen peroxide, rinse a couple times and you are set. We also offer variants on hydroton, including Growstones, which are made from recycled materials, as well as Sunleaves Rocks, which is made with shale right here in the United States! We also offer Botanicare Hydrolitle, which is great for mixing with potting soil. Have questions about your grow medium or your hydroponic growing system? Contact the helpful staff at Horizen Hydroponics here.