MarineLand Magnum Filter Plug

This cap can be used to replace the foam ring for the MarineLand Magnum filter.

The MarineLand polishing filters, especially the original filter, are a bit too short to fully seal at the top and bottom (see red arrows in one of the photos). If you have ever found hair or any debris on the impeller, this is because dirty water is bypassing the filter media.

Instead, install the filter securely onto the pump head, and use this plug in the bottom of the filter. This will ensure all water is properly filtered.

This video goes into more detail: 

Hand wash in warm soapy water. No hot water. No dishwasher.