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.
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.