House & Garden Coco Medium is 100% coco coir with little to no sodium residuals and is very clean without anything added. Buffered with calcium nitrate and then washed. During the washing process, the nitrate is removed, and only the calcium stays behind. The coco larger fiber coir holds onto water and nutrients; does not get compacted easily like shorter fiber coir. Add 10–20% grow stones or chunky perlite for best results and drainage.