I use 5-1-1 and or 5-2-1 (Bark, peat, perlite) Plants grow fine, but does require little more frequent watering. I am also doing an experiment with a new citrus tree. I am growing the tree in 100 percent pumice. Pumice holds more water and more air then does other lava rocks such as scoria. Further differences, lava is a rock, pumice is a volcanic glass. Both contain a multitude of open crevasses/tunnels that holds extra air/water throughout the particles. I just started with this new medium, so it will be a while to determine it value to growth and health of a citrus tree.