Box filters are suited to small aquaria with minimal loading and breeding tanks. They utilise the airlift principle to gently draw water through the box. The box is usually filled with filter floss or gravel to provide mechanical and biological filtration and can be supplemented with a variety of chemical media. As the boxes are unsightly and relatively large for the aquariums they service, they have generally been superseded by more complex systems.

Box filters are however extremely useful to house specific chemical media in certain instances, for example one may fill the filter with activated carbon to remove traces of medication after treatment, or fill with peat to help soften the water in breeding aquariums.