Abstract: A biological air filter for cleaning, humidifying, and detoxifying air containing harmful substances, having a generally cylindrical filter housing with a sealing cover and a removable filter element. The filter element contains a substrate and plants. Air is circulated through the moist substrate and released into the room. Dust and harmful substances are trapped in the substrate and are at least partially consumed by the plants. The biological air filter can also be connected to an existing ventilating system. It is decorative and suitable for use in offices, apartments, laboratories, doctor offices, and the like.

Abstract: A set for the hydroculture of plants comprising a plant-receiving vessel and at least one ancillary device such as a water-level indicator, structure being provided on said vessel and said ancillary device for removably connecting the ancillary device to the vessel wall from the exterior, it being thus possible to attach or remove the ancillary device at any time whether a plant be contained in the vessel or not.

Abstract: The invention concerns an accessory unit for plant receptacles for hydroponics, this accessory unit forming the water-level gauge-channel and the pouring-in-and emptying-channel, both of the channels being placed close to each other, rigidly connected together but separated along their whole height by a partition wall.