In the humble opinion of this experienced planted tank enthusiast...substrate should never be the primary source of nutrients for your plants. Why? Because it gets used up, and you just end up fertilizing anyway. I tend to use ADA Aquasoil, but not really for its chemical properties...rather for its mechanical properties. It is easy to plant, and it doesn't compact. I think you will find Fluval Stratum to be similar in that way. I will say though, that I have also grown fabulous plants in Flourite, both original and sand versions. Either way, use good water column ferts, and/or root tabs for root feeders like swords and crypts.