Coco and peat moss are common soil amendments. They improve the aeration abilities of the soil. I use a rough mix of 50% soil and a 50% addition of half peat moss and half coco. The coco is washed and buffered prior to mixing. I do a 24 soak in calmag after it's rinsed.
After I mix the soil/coco/peat I use crushed pumice stone. I like it a ton better as it doesn't float to the top of the soil. Costs more but is so much better. I am for about 15 to 20% by volume of stone to soil.