Your plants will be living in this there entire life so its important to choose the rite growing medium for you. There are many different brands that make growing media like for instance Grow It Yourself Hydroponics recommend Canna Coco Pro Plus which is a coco medium. Biobizz also produce great mediums such as there Lightmix and Allmix. You have Clay Pebbles which are mainly used in Hydroponic Systems like the Alien or IWS these are Flood and Drain Systems. Some Deep water Culture (DWC) Systems use clay pebbles too. You can aslo add mixers like perlite and vermiculite to enhance your medium for oxygen. Rockwool is very popular for starting young plants. Good brands of rockwool include Cultilene and Grodan.