Although you can grow plants in anything from chicken grit over laterite clay, fluorite, eco-complete, schultz aquatic soil, pool filter sand over gravel fert tabs and or laterite, seachem onyx sand and even gravel capped over top soil, some substrates, with all other things being equal tend to give better results than others. The way I look at it, you want your substrate to be a one time expense and not have to tear down a tank to replace a substrate at least not for a few years. Keeping this in mind, I would suggest biting the bullet and getting ADA Aquasoil Amazonia I or II. Many members who have grown plants in Eco-Complete, Schultz Aquatic Soil, Fluorite, etc., including Tom Barr state that nothing compares to Aquasoil for plant growth. I cannot speak to this as I just set up a test tank to see what the hype is all about, but if so many members are saying nothing but good things about it, then it cannot be all bad.