I run a phosban reactor with GFO (Granulated Ferric Oxide). Phosban, Rowaphos, and Phosar are all band name GFOs. GFO is able to bind with phosphate and the phosphate is therefore "removed" from the system. There are differences between them and while Rowaphos has more binding capacity than Phosban it also cost proportionally more. I use Phosar (cost effective - especially in bulk). Phosphate is continually added to your system (primarily in food) and is one of the primary sources of nuisance Algae.
I also use carbon in a separate reactor. Carbon is a good all round media that is able to bind to a whole host of pollutants in your system (but not phosphate).