Better off buying str8 GFO
(granulated ferric oxide) from somewhere like bulkreefsupply, same stuff. You can mix carbon with it as it has a tendency to clump and reduce effectiveness.
It does work as a PO4
reducer. Follow manufacturers/vendor instructions.
W/ research you'll find that all GFO
comes from one manufacturer, name brand gets you added cost...
Phosphate reduction takes time. Watch what you feed or you'll just end up feeding the po4
Not sure about the advantages of tumbling Purigen.. Can't hurt I guess, would bet it doesn't help much.