CocoTek? Premium Coir is naturally free of bacteria, plant disease, fungal spores, weeds, seeds and pathogens. General Hydroponics? CocoTek? growing medias can be used by themselves, blended together, or mixed with expanded clay pebbles, perlite, topsoil, or any other growing media. CocoTek? Premium Coir contains pre-treated coco coir and can be used by itself or blended with other media to create your ideal mix.