An internal filter, often called a “canister” or “submersible pump” by aquarists, is one of the most common and affordable devices for maintaining water purity in a freshwater aquarium. Its compactness, ease of installation, and high efficiency in mechanical filtration make it an indispensable element for many aquarium systems, especially those of small and medium volumes. However, like any piece of equipment, the “canister” has its limitations, and its effectiveness directly depends on correctly matching its power to the tank’s volume and bioload.
