Phosphate remover

no one can say how long you can use any chemical media in your tank!!..whether its carbon, gfo, phosguard ect----every aquarium is different and has different levels of doc's that are needed to be removed...example....tank 1---100 gallons, good skimmer, med bio-load-----tank 2...100 gallons, no skimmer heavy bio-load...5oz of the same chemical media will not work the same in these 2 100g aquariums....use and monitor, thats the key to any chemical filter media!!