Germicidal Light Bulbs are a specialist lamp that emits short wave ultra violet UV-C radiation for killing bacteria and other micro-organisms in water and air purification units. This 13 Watt Ultra Violet Germicidal Compact PLS Fluorescent Lamp is an energy efficient long life bulb that reduces energy usage by 80%. Common applications are pond filtering and disinfection of drinking water. Warning do not look directly at this light source as UVC radiation is harmful to the human eye.