A pool cleaner, compromising: a canister body including an inlet, a top, and a bottom having a central opening, the canister body defining an inner chamber; a filter medium disposed within the inner chamber of the canister body; a cyclone block including a plurality of cyclone containers and a central opening, the cyclone block disposed within the inner chamber of the canister body and at least partially surrounded by the filter medium; a top cap including an outlet, the top cap covering the cyclone block; and an impeller subassembly comprising: a sleeve having a first end and a second end; a shaft including a first end and a second end, the shaft positioned within the sleeve with the first end of the shaft extending from the first end of the sleeve, the shaft being rotatable within the sleeve; a retention ring connected to the shaft and configured to prevent the shaft from being removed through the central opening of the bottom of the canister body; an impeller engaged with the first end of the shaft; and characterized by: a guard secured to the sleeve and to the top cap at the top cap outlet; at least a portion of the impeller subassembly being positioned within the inner chamber of the canister body with the sleeve and shaft extending through the central opening of the cyclone block and positioned at least partially within the cyclone block with the second end of the sleeve being adjacent the central opening of the canister body; wherein the guard can be disengaged from the top cap allowing the impeller subassembly to be removed from the inner chamber of the canister body and the cyclone block as a single unit; and wherein a first cyclonic flow is generated between the canister body and the filter medium, and a second cyclonic flow is generated within each of the plurality of cyclone containers. a canister body including an inlet, a top, and a bottom having a central opening, the canister body defining an inner chamber; a filter medium disposed within the inner chamber of the canister body; a cyclone block including a plurality of cyclone containers and a central opening, the cyclone block disposed within the inner chamber of the canister body and at least partially surrounded by the filter medium; a top cap including an outlet, the top cap covering the cyclone block; and an impeller subassembly comprising: a sleeve having a first end and a second end; a shaft including a first end and a second end, the shaft positioned within the sleeve with the first end of the shaft extending from the first end of the sleeve, the shaft being rotatable within the sleeve; a retention ring connected to the shaft and configured to prevent the shaft from being removed through the central opening of the bottom of the canister body; an impeller engaged with the first end of the shaft; and characterized by: a guard secured to the sleeve and to the top cap at the top cap outlet; at least a portion of the impeller subassembly being positioned within the inner chamber of the canister body with the sleeve and shaft extending through the central opening of the cyclone block and positioned at least partially within the cyclone block with the second end of the sleeve being adjacent the central opening of the canister body; wherein the guard can be disengaged from the top cap allowing the impeller subassembly to be removed from the inner chamber of the canister body and the cyclone block as a single unit; and wherein a first cyclonic flow is generated between the canister body and the filter medium, and a second cyclonic flow is generated within each of the plurality of cyclone containers. a sleeve having a first end and a second end; a shaft including a first end and a second end, the shaft positioned within the sleeve with the first end of the shaft extending from the first end of the sleeve, the shaft being rotatable within the sleeve; a retention ring connected to the shaft and configured to prevent the shaft from being removed through the central opening of the bottom of the canister body; an impeller engaged with the first end of the shaft; and characterized by: a guard secured to the sleeve and to the top cap at the top cap outlet; at least a portion of the impeller subassembly being positioned within the inner chamber of the canister body with the sleeve and shaft extending through the central opening of the cyclone block and positioned at least partially within the cyclone block with the second end of the sleeve being adjacent the central opening of the canister body; wherein the guard can be disengaged from the top cap allowing the impeller subassembly to be removed from the inner chamber of the canister body and the cyclone block as a single unit; and wherein a first cyclonic flow is generated between the canister body and the filter medium, and a second cyclonic flow is generated within each of the plurality of cyclone containers. at least a portion of the impeller subassembly being positioned within the inner chamber of the canister body with the sleeve and shaft extending through the central opening of the cyclone block and positioned at least partially within the cyclone block with the second end of the sleeve being adjacent the central opening of the canister body; wherein the guard can be disengaged from the top cap allowing the impeller subassembly to be removed from the inner chamber of the canister body and the cyclone block as a single unit; and wherein a first cyclonic flow is generated between the canister body and the filter medium, and a second cyclonic flow is generated within each of the plurality of cyclone containers.