I bought a used Hayward Star-Clear C-1750 filter last year and have purchased new cartridges but still have particulate coming through the return (although, interestingly, the water is totally clear until ten minutes or so after installing the new or freshly cleaned cartridge).
When I look,at the parts diagram for these filters, I see a part that did not come with my used filter. It is the Guide Cone . I also am missing the washers associated with the guide cone, as well as the "e" clip.
The top half of this filter housing has a cylindrical sleev the seems to fit down into the cartridge as the top is tightened to the base. It doesn't seem like there is even room for this Guide Cone.
I am wondering if pressure builds within the filter after that first ten minutes (of a freshly installed cartridge) enough for some of the water to push past the "sleeve" and head directly out to the return, unfiltered. Does that Guide Cone serve as a gasket of some kind as well?