[jeff]

for these one I use just pur gypsum + river sand 50/50


for the mexican and a lot of temperate

50% cat litier ( with some time AKADAMA ( bonzai clay))
12.5% pouzzolane ( volcanic rock)
12.5% river sand
12.5% calcareous sand
12.5% vermiculite

for others temperates

blond peat + vermiculite 50/50

for the subtropical US

blond peat + river sand 30/70

jeff