Coralife Turbo-Twist UV Sterilizers are the most efficient devices for ultraviolet sterilization on the market today. They feature a quartz glass sleeve with a PL compact fluorescent UV lamp surrounded by a revolutionary "Turbo-Twist" flow design to increase dwell time, which in turn increases efficacy. Continuous ultraviolet sterilization of your water eliminates single-cell algae for crystal-clear aquariums and also eradicates most harmful microorganisms on the initial pass through the chamber. Its triple-treatment time fully utilizes all the available UV output of the lamp and ensures that disease-causing pathogens cannot reproduce, thus decreasing the possibility of a disease outbreak in your system. Coralife Turbo-Twist UV Sterilizers have been designed for use in all freshwater and saltwater aquatic systems. Turbo-Twist 3x: 9 watt, treats up to 125 gallon saltwater or freshwater aquariums Turbo-Twist 6x: 18 watt, treats up to 250 gallon saltwater or freshwater aquariums Turbo-Twist 12x: 36 watt, treats up to 500 gallon saltwater or freshwater aquariums