Pool & Spa Filter End-Cap Types Explained
Cartridges are matched not only by length and diameter — the top and bottom end styles matter just as much.
Open hole end
A round opening through the centre of the cap. Measure the inside diameter of the opening.
Closed end
No centre opening. Some closed ends include a handle or raised moulding.
Handle top
Makes removal easier. The handle shape must clear the housing lid.
Threaded bottom
Screws into the housing. Measure the outside diameter of the thread.
Spigot bottom
A raised male fitting that pushes into the housing. Measure the outside diameter of the spigot.
A cartridge can match on length and diameter but still have the wrong end caps. Always check the top end, bottom end, hole opening and thread or spigot size, and confirm on the product listing before ordering.
Not sure which one? Use our Pool & Spa Filter Cartridge Finder to search by length, diameter, end-cap type, hole size and thread or spigot size.