Phosban-Phosgaurd

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PhosBAN (made by Two Little Fishes) is granular ferric oxide (GFO).

PhosGUARD (made by Seachem) is aluminum-based.

Both are designed to remove phosphate from the water column and both work. There's been recent concern over the use of PhosGUARD in reef tanks as aluminum has been shown to be harmful to invertebrates.

Other products such as Rowaphos and Phosar are also GFO.