Abstract: A pool or spa sterilizing device is provided including a housing having an interior space. An ultra-violet tube is positioned in the interior space of the housing and is adapted to emit ultra-violet radiation upon the receipt of power. A power cord is included having a first end with a standard grounded power plug for being releasably connected with an alternating current receptacle and a second end electrically connected to the ultra-violet tube. As such, power is supplied to the ultra-violet tube upon the plug of the power cord being plugged into the current receptacle.