I've looked at their instructions before and I don't know to calculate a dosage. The other products all say something along the lines of "1 ml in X gallons of water will reduce phosphates by Y ppm". Seaklear says if your phosphates are at e.g. 250 ppb (0.25 ppm) then dose 1 ounce per 1000 gallons of water, but doesn't tell you how much of that 250 ppb will be removed.Could you do the same for the Seaklear Phosphate remover?