I grow with coco only in smartpots that I hand water. Ive tried many other mediums in the hydro/soilless arena, and plain coco is the easiest and best that I have used. Water retention, speed of growth and huge yield are all benefits of coco only in smartpots. I agree with SeaMaiden about the differences in ph and
cal-mag needs for the mix your trying to run. While I know that a lot of people use coco mixes, I can tell you that coco alone is the way to go. With 30-40% porosity depending upon the brand you use, theres no need for perlite. I run 15,20, 25, and 30 gal smpots depending upon the size of the plant. 5 gals will work fine though. The only thing that I do to plain coco is put a small layer of
diatomaceous earth on top to kill gnats and also act as a thermal insulator to keep my roots a steady temp through day and night cycles. I hope that helps.