Hose connector adapter apparatus for an evaporative cooler float valve includes an integral ferrule for sealing the float valve to the adapter and an internal hexagonally configured passageway through which the water flows and which passageway receives a hex wrench or the like for securing the adapter to the float valve when there is insufficient external clearance for manually securing the adapter to the float valve. The adapter apparatus is able to be secured to evaporative cooler float in virtually any location on a cooler housing, regardless of the cooler housing configuration either by manually securing the adapter or by using a wrench internally.