Filtering device (20) to draw water from an aquarium and the like and make water circulate inside, including a container (30) comprising a first housing portion (32) having a first inlet (174) and a second inlet (176) for the entry of water taken from the aquarium into the first housing portion (32) which is able to contain at least one filter for filtering water, further including a flow control device (50) having an entry (60) for taking water from the aquarium and it has two operating positions, a first operating position or filtering position wherein the entry (60) is in communication with the first inlet (174), so that water taken from the aquarium is put into the first housing portion (32), passes through the first inlet (174), is filtered and then is put back into the aquarium, and a second operating position or cleaning position or backwash position, wherein the entry (60) is in communication with the second inlet (176), water taken from the aquarium enters into the first housing portion (32) through
