Reference
Guides
A small set of background notes. The structured filter and part pages are the reference itself — these explain how to read them.
- 01How to identify your aquarium filter modelWhere to find the exact model name and number on a hang-on-back, internal or canister aquarium filter, so you look up the right cartridge.
- 02OEM-listed replacements vs third-party compatibility claimsWhy "the manufacturer lists this cartridge" and "a seller says this fits" are different kinds of information, and how to weigh each one.
- 03What "compatible with" actually means on a cartridge listingA practical way to read "compatible with", "fits", and "replacement for" on third-party aquarium filter listings, and the traps in each.
- 04Why two similarly named filters can use different cartridgesNear-identical model numbers across aquarium filter ranges often map to different cartridge sizes. Here is how to avoid ordering the wrong one.