Waterfall bio-filter has high efficiency biological filtration function, it draws water from the aquarium through the input assembly and into the input section. The water flows must passthrough the double bio-sponge foam insert which strips most particulate matter from the passing flow and holds it. The flow diverter directs the flow beneath the filter chamber. The filterd water is forced through the entire foam filter insert actived carbon, ceramic rings, filter sponge, bio-sponge to trap suspended particles and then to absorb liquified wast.