I bought 50 or 75? Bags of the medium conifer mix last spring, I also purchased 25 bags of Akadama from Fred. The Akadama is heat treated like the old double red line Akadama. However, it is somewhat softer than the old stuff. The premix is interesting, I have been sifting the soil down in to three sizes and dust, I then blend in sifted and sized lava. Unlike Clay King or Aoki blends, this soil needs to be heavily sifted for sizing at least.
The heating to 300 degrees C eliminates live organisms in the Akadama and allows t to pass USDA APHIS inspection.