The right filter suits the aquarium and is practical to maintain. Start with the fish, actual water volume, tank layout and available installation space. A larger litre-per-hour number alone does not make a better choice.
Compare the four common options
Air-driven sponge filter
Water is drawn through a sponge by the air-driven lift. It can provide mechanical and biological filtration with adjustable air delivery. Consider it where a suitably gentle intake and simple access are useful, but match its capacity and circulation to the setup. It needs a compatible air pump, and new media must mature. Read the sponge-filter setup guide.
Internal power filter
An internal filter keeps the pump and media inside the aquarium. Check the space it occupies, required water level, intake protection and outlet adjustment. Access may be convenient, but a strong direct jet can be unsuitable for some residents. Model specifications matter more than a universal tank-size cutoff.
Hang-on-back filter
A hang-on-back filter places its body on the aquarium rim. Check clearance behind the tank, rim and lid compatibility, water level and restart requirements. Some designs need manual priming; others differ. Evaluate the actual media arrangement and replacement instructions rather than assuming every cartridge system works identically.
External canister filter
A canister keeps the main body outside the tank and routes water through hoses and media baskets. Allow access for servicing and check the manufacturer's installation-height limits, hose routing, seals and priming procedure. It is an option for many setups, not an automatic upgrade for every tank.
Check working flow, not just maximum pump output
Compare what each manufacturer means by its flow rating. Pump output, circulation through installed media and performance in your layout are not necessarily the same measurement. Hose configuration, media and maintenance can affect performance; do not assume every filter delivers half its advertised flow or impose one turnover target on all species.
Use the manufacturer's aquarium range as a starting point alongside stocking, waste load and fish behaviour. Our filter-flow check explains how to recognise a current that prevents fish from resting or feeding.
Plan media and maintenance together
Mechanical media traps particles; biological media provides colonisation surfaces; chemical media has a product-specific purpose. None removes the need to test and maintain the aquarium. See filtration basics for how these functions work together.
Follow the maker's service schedule and media instructions while avoiding unnecessary replacement of all established biological media at once. Do not ignore required cartridge changes or repack a filter in a way that blocks its intended water path. For canister care, use our cleaning guide with your model's manual.
Before you buy
- Record tank dimensions in mm, actual water volume and planned adult livestock.
- Check space, lid clearance, water level and safe electrical installation.
- Confirm included media, compatible accessories and replacement parts.
- Review priming, maintenance access and the power-interruption restart procedure.
- Plan biological maturation before relying on a new filter for a stocked aquarium.
Browse aquarium equipment and compare the exact model instructions. For general design differences, Aqueon's filtration overview is a useful starting point; its examples do not replace another manufacturer's manual.