I may be overly suspicious as on the product page they explicitly say it does not contain "aluminum or lanthanum compounds."
I still suspect they are misleading with how they advertise it.
It's a blend of different ingredients and they often talk about one of the ingredients and imply it's the primary agent without actually saying it. So when they say it's a "biological phosphorus removal product" I suspect they are saying it contains biologicals in addition to some other, probably much more active, chemical ingredient. Indeed at one point they say
"MetaFloc works best in water temperatures above 50°F when bacterial activity is optimal. It can still provide phosphorus binding through the flocculant component in colder water, but the biological activity that provides long-term sediment control is reduced below 40°F. For best results, apply during the growing season."
