I actually have pictures of the twoside by side..not that you can tell a huge difference, but as mentioned if one thing came to mind it's that flourite tends to be smaller, sharper edged particles while the eco complete tends to be rounder. There are varying sizes of "particualte" with the Eco with the idea being over time it settles into two layers, I just can't recall which from the lable but I think it's the larger pebles on top with the finer grains settling lower, but check the label. Without the technical promises, differences are mainly pepple shape.
AS for colour, I've always been a fan of black, but it's personal choice
AS for colour, I've always been a fan of black, but it's personal choice