something that will grow plants well, but I don't exactly have the money for the expensive fluorite, but would sand work? I could aerate it with an air wand.
i definitely would go with laterite.. it's cheap and can transform regular gravel into an excellent substrate for plants.
i would stay away from root tabs unless youre trying to grow big heavy root feeders like amazon swords and the like.. theyre easily stirred up and tend to cause lots of problems (algae) when they do.