Aquarium filter

Claim 1

A SUBMERSIBLE FILTER FOR CONDITIONING AN AQUEOUS MEDIUM COMPRISING IN COMBINATION: (A) A POROUS PHYSICALLY SOLID CYLINDRICAL FILTER MEDIUM HAVING ITS OUTER SURFACE PROVIDED WITH A PLURALITY OF CIRCUMFERENTIALLY DISPOSED SPACED FLUTES PARALLEL TO THE AXIS OF SAID MEDIUM, AND HAVING A HOLLOW CORE FORMED BY AN AXIALLY EXTENDING BORE, THE PORES OF SAID MEDIUM BEING THE SOLE INLET OF AQUEOUS MEDIUM INTO SAID BORE; (B) A CAP FOR CLOSING SAID BORE AT ONE END OF SAID CYLINDRICAL MEDIUM AT THE LEAST SUBMERSIBLE EXTREMITY, SAID CAP HAVING A DEPENDING SKIRT INTEGRAL THEREWITH AND ADAPTED TO BE REMOVABLY INSERTED INTO THE BORE OF SAID FILTER MEDIUM AT ONE EXTREMITY, BUT SAID CAP HAVING LOCATED THEREON, AND EXTENDING THERETHROUGH A PAIR OF INTEGRALLY CAST NIPPLES, (C) A WEIGHTED BASE HEAVER THAN SAID CAP ACTING AS BALLAST FOR SAID FILTER MEDIUM, AND HAVING A CYLINDRICAL WALL PORTION INTEGRAL WITH A SOLID DISC PORTION AND ADAPTED TO BE REMOVABLY INSERTED INTO THE BORE OF SAID FILTER MEDIUM FOR CLOSING THE BORE AT THE OTHER END OF THE CYLINDRICAL MEDIUM AT ITS DEEPEST SUBMERSIBLE EXTREMITY; (D) AN INLET TUBE FOR INTRODUCING AIR INTO SAID BORE, SAID TUBE EXTENDING THROUGH, AND FRICTIONALLY HELD IN, ONE OF SAID PAIR OF NIPPLES IN SAID CAP, INTO SAID HOLLOW BORE TO A POINT ADJACENT SAID BASE, AND (E) AN OUTLET TUBE OF PREFERABLY LARGER DIAMETER FOR EXITING AIR AND WATER FROM SAID BORE, SAID TUBE EXTENDING FROM THE OTHER ONE OF SAID PAIR OF NIPPLES IN SAID CAP INTO THE AQUEOUS MEDIUM OUTSIDE SAID FILTER MEDIUM.