The V2 Power Box Water Clarity Filter Pad for freshwater releases a flocculant which clumps together fine particles suspended in the water, making them easier to filter out, enhancing & improving aquarium water clarity. Fits perfectly into the V2 Power Box External Filter Model 200 For best results Always ensure good water flow through the filter pad Replace every 4 weeks For optimum results a filter fleece should also be used in your filtration system to ensure the flocculated particles are removed