Our world-famous, Patented phosphate eliminators! Alumina-free, non-toxic ""phosphate magnets"" remove only soluble and insoluble phosphates - not expensive essential trace elements! PF - 100 includes red and hair algae additive for fast elimination of unsightly debris, PH - 200 is for general phosphate level maintenance, Both are 100% safe for application in marine and reef systems, SKU: RPS31211