Diatom Filter Bags (model P-4 & XL-4) will wear out around the top port where the solid plastic is bonded to the filter bag material. To extend the life, apply a thin layer of silicone rubber to the top of the fabric extending out from the ridged plastic port 1/4" to 1/2". Make your silicone layer a little thicker next to the black plastic, then taper the silicone down as thin as possible. This will give the fabric a larger flexible area. But remember you are also blocking flow area so don't overdo a distance of 1/2".