Hydroponic grow mediums are simply soil-less material that supports the plant weight and hold it upright. It is generally porous so it can hold the moisture and oxygen that the root system requires to grow. Grow media are inert and do not provide nutrients. The nutrients that plants need are provided by the nutrient solution and is what the growing media is watered and moistened with.Choosing the right grow media is crucial and essential. Choose one that suits both the needs of the plant and needs of your system. Water retention, aeration and pH balance are all aspects that vary depending on the medium and must be considered when making the final choice. Some of the most widely used growing media are coco, clay pebbles, rockwool, perlites and vermiculites, pot mixes.