It took alot of reasearch but I was looking at this same comparison. I decided to do a solid layer of floramax in my 40 gallon breeder then cap it with eco complete. The only real difference is the age of the volcanic rock. From what I have read the floramax is a little sharper sometimes but I rinsed out 2 bags this weekend and it feels just the same as eco to me. I didnt want to pay for the water in the bags of eco so I'm doing 2 bags of eco on top of however many bags of floramax it takes to cover my tank.