I must be doing something wrong with this mineralized soil process.
So, I was. Turns out I wasn't doing the soak right, I was literally running the hose into a bin of the soil and letting it overflow for awhile, but I guess that was washing away most of the stuff you actually want to keep :-/
Anyway, I said screw it and went out to buy some CaribSea Super Naturals Tahitian Moon Sand... I'm going to do a test mixing some clay into it but will probably just end up using that plus the 45G of Flourite Black Sand in my 29G, plus some root tabs.