UV (Ultraviolet) Sterilizers in Your Marine Aquarium

Ultraviolet light is broken into 3 classifications: UVA, UVB and UVC. UVA is also called Ultraviolet A, long wave, or black light and has a wavelength range of 315 nm–400. UVB, also called Ultraviolet B or medium wave and has a wavelength range of 280 nm–315 nm. UVC, also called Ultraviolet C, short wave, or germicidal UV has a wavelength of 100 nm–280 nm. Ultraviolet Sterilizers used in the aquarium trade utilize bulbs which create light in the UVC wavelengths.

Ultraviolet Sterilization has been used for some time in aquariums to both eliminate Green Algae suspended in the water column and to kill parasites in the water column. Many experienced marine aquarists believe that ultra violet sterilization is one of the most effective means of disease prevention in aquariums and for general water quality control in aquariums.

From Carl Strohmeyer's UV Sterilization (How UVC Sterilizers Work) article: "It appears that the UVC radiation which is contained in the UV Sterilization unit breaks down oxidizers in the water column that would otherwise lower a fish’ immunity (Redox Balance), this benefit is often ignored as many only focus on the germ, single cell parasite and algae killing abilities of UV Sterilizers. Redox Balance is basically the oxidation and reduction properties of water. This is very important for proper breakdown of organic waste (the oxidation side of Redox). Most experts now agree that the Redox should be +300 to -100 mV for marine or +125 to -200 mV for freshwater for healthy fish immunity, which a UV Sterilizer can help maintain." ORP Monitors measure the Oxidation Reduction Potential in your aquarium.

UV Sterilizers are available in a number of sizes, with differing wattage and GPH ratings. Which one is right for your needs? It depends on what you want to accomplish:

• Water clarity (free-floating algae control) - 40-50 gph per watt.
• Sterilizing (bacteria and virus control) - 20-25 gph per watt.
• Sterilization for single cell parasite control (such as Cryptocaryon) and stubborn viruses - Under 10 gph (or even less) is necessary.

Some UZ Serilizers are more efficient than others at keeping the "target" organism in front of the UV light longer ("dwell time"). For example, the Turbo-Twist UV Sterilizer by ESU twists the water around the UV light up to twelve times (depending on the model) before it leaves the sterilizer. This greatly increases the dwell time the organism spends exposed to the UV light on each pass through the unit. The Lifegard Aquatics Aquastep Pro UV Sterilizer uses a ladder design which slows the flow rate to triple UV exposure time.

The flow rate (gph) can be adjusted on most UV Sterilizers by installing an adjustable valve between the Sterilizer and the pump supplying the water.

Read More About Ultraviolet Sterilization and It' Uses.