now you take the strainer cone of the power head and attach the extension tube to the strainer cone. now cut the top of a 2 liter bottle and stick the tube and strainer cone on the bottom standing up. now fill up with gravel. leave 2" of space from the top of the bottle or top on the tube, whichever is shorter. now just cut strips of poly-fill pad cut into circles and place them on top of the gravel as a mechanical filter. then place the power head onto the top of the tube an there you go. a very powerful bio filter!
this is mine that i made, can filter a 29g over stocked!! cichlid tank, and a very heavily stock turtle tank
