An ozone injector device comprising a housing having a water passageway through the housing, a corona tube disposed within the housing, an ozone inlet fitting removably coupled to the water passageway, the ozone inlet being in fluid communication with the corona tube via a corona discharge tube, and a clearing piston positioned to move into and out of the water passageway directly opposite the ozone inlet. The clearing piston is biased upwards, towards to the ozone inlet, and configured to prevent flow of ozone into the water passageway.