I grow my crypts, submersed/emersed and I used some Seachem florite and also laterite. The laterite was from gravel I introduced when I upgraded my tank from a 29 to a 75.
I also have a question for you guys (sorry to take control of the post):
Do any of you crypt keepers use liquid fertilizer in your tanks? I have some Seachem Flourish but I don't want to use it if it will promote algae growth. I feed my fish twice a day, and I read that in many situations this can be sufficient fertilizer. I don't dose CO2 and only use 110 W of my 220W PC fixture. I also use RO water exclusively and on occasion add this electrolyte solution. I also have Java Moss and Fern, so since they are epiphytes, I am unsure if I need the Flourish.