i have fss and it does ok with hc, its kinda light for a substrate so it might take a while for the hc to root well. most people tend to do dry start with hc any way. fss does not leach ammonia and i put my shrimp in with in hours of setting up the tank. DO NOT DO THAT!!!! i had other plants, mosses, dechore and what not that had biofilm in the tank for them and have started many tanks this way. i used rili in this tank for a while with no prob but it does tend to buffer the ph lower than say sand. every one seems to have different results with fss. for some it barley buffers their water for me it takes it down from 7.4 ph to about 6.