Abstract: A pressurized percolating filter, of the type used for the regeneration of water in aquariums, comprising, a closed receptacle (1), having: a prefiltering chamber (2), defined by a perforated bottom (3) equipped with a uniform plurality of perforations (3c), an intermediate chamber (4), a percolation chamber (5), and a collection chamber (7) for the regenerated water-communicating with an aquarium tub (8) by means of a feed pipe (9). A mixture of air and water to be regenerated is fed from a single leader pipe (10) to the prefiltering chamber (2). The prefiltering chamber (2) comprises in the perforated bottom (3) a small tub (3a): equipped at its bottom with a smaller number of calibrated perforations (3b) than those (3c) in the perforated bottom (3), and equipped with a float valve (12) controlling an inflow perforation (13).