Stage 1) Foam Insert - Particulate waste is trapped and builds up over time. The Insert can often be re-used, if rinsed of debris and replaced within the first chamber.

Stage 2) Ceramic Nodes - These remain useful for an extended period of tie. Since they are porous they do eventually clog and will require gradual exchange. You should always maintain the nodes during a regular water change. Save a bucket of used aquarium water and rinse the nodes thoroughly in it to remove debris in the biological chamber. When exchanging nodes, do it gradually, replacing no more than half at a time. This will allow the older nodes to rapidly seed the new ones and ensure biological filtration continues unabated.

Stage 3) UltraGrade Carbon insert - Carbon remains active for a relatively short time, its internal matrix actively adsorbs liquefied impurities, dyes and medications and gradually fills and clogs the pores. As this occurs, the carbon loses its ability to clarify water. In most cases carbon should be replaced every two weeks to ensure a crystal clear aquarium.