Yes, I've been trading emails with Aaron about this. I was concerned that it doesn't quite meet the mineralized clay recipe. However, the red clay in the recipe, I believe, was for adding iron to the substrate and I have the Flourite to do that. So, I'm thinking that the montmorillonite should work okay. I'm still soaking the topsoil so I will be a few more days before the tank is setup. I'll let you know how it goes!