The device for filtering water and maintaining biological equilibrium in an aquarium forcibly directs water through a cycle, where it is purified in several steps. Excess waste materials from the vital activity of hydrobionts threatening to disrupt the biological equilibrium in the aquarium pass downwards through an opening in a false base, where a flow of water carries said excess waste materials to an outlet pipe (variants 1, 2) or to a vertical part of a cavity (variant 3), from where the water with the waste materials is sucked in by a water-raising device, and carries said waste materials upwards into a container with soil. Here, the purification is continued in a process in which the water seeps through the soil - the waste materials which are not processed by bottom microbes are used as food for soil microbes and subaerial plants. The lighting equipment arranged here, by virtue of the light emitted thereby, causes the process of plant photosynthesis, which accelerates the utilization of the waste materials by the plants. The purified water is discharged into the aquarium. At the outlet of the container, the flow (variant 1) through the pipe carries away the water into the interbase space or (variants 2 and 3) drops in a corner far away from the water-raising device, where it continues to circulate to the outlet pipe of the false base, thereby capturing the waste materials.Un dispositif pour filtrer leau et maintenir un équilibre biologique dans un aquarium envoie leau dans une cycle de circulation pendant lequel leau est purifiée en plusieurs stades. Les déchets excédents des activités vitales des hydrobiontes qui menacent de perturber léquilibre biologique dans laquarium circulent vers le bas à travers des orifices puis sont emportés par le flux deau vers une tubulure de sortie (var. 1,2) ou vers la partie verticale du plan (var. 3) doù leau avec les déchets est aspirée par le dispositif de levage deau et les porte dans un récipient avec le sol. A ce niveau,
