Don't use either, both are a waste of money. I was talked into using Flourite in my 70g some years back, and it nearly killed my cories within a matter of days. I moved them to a tank with play sand and fortunately they recovered, though one panda still has a third of its lower mouth missing, but it did heal. After a further two years, the plant growth was disappointing and I tore the tank down and dumped the Flourite in a corner of the back garden. Plants will grow just as well in inert play sand, with substrate fertilizer tabs for large plants.