External filter

External Filter – Powerful Filtration for a Healthy Aquarium

An external filter is one of the most effective ways to keep your aquarium clean and thriving. Unlike internal filters, external filters are placed outside the aquarium – usually in a cabinet underneath – and pump water through one or more media baskets before returning it to the tank. This makes them an excellent choice for those who want powerful filtration without sacrificing space inside the aquarium.

Three Filtration Stages in One

Most external filters offer complete three-stage filtration: mechanical filtration that captures dirt and particles, chemical filtration, for example with activated carbon that absorbs toxins and bad odors, and biological filtration where beneficial bacteria break down ammonia and nitrite. Together, these stages create a stable and healthy water environment for your fish and plants.

Suitable for Most Aquariums

External filters come in many sizes and capacities, from compact models for smaller tanks to high-capacity filters for large aquariums. A general rule is that the filter should circulate the entire aquarium volume at least four to five times per hour. If you choose a filter with a little more capacity than you need, you will get quieter operation and longer intervals between cleanings.