UV sterilizer is a tube of filtered ultraviolet light which destroys the DNA of any single cell organism that passes through it. It is used to control infections by stopping the spread of microorganisms from one fish to another through the water. It is also used in pond applications or an aquarium to control free-floating algae.
Although a little algae is helpful in creating oxygen and stabilizing the water environment, in large amount it becomes a serious problem. Algae can make your fish and plant life sick as it takes away its main source of nutrients. Cleaning your aquarium of unwanted algae, parasites, and bacteria repeatedly can be irritating. Using an an aquarium UV sterilizer can be beneficial in this case as UV sterilizers are effective in eliminating common pests from your aquarium.
However, it can cause cancer and other diseases if not used carefully.
Types of UV sterilizers:
Mostly UV sterilizers comes in a tube like design which contain an in and out flow. Some UV sterilizers come with its own water flow while others are required to be connected with the outflow of your filter's canister. Make sure that the UV sterilizer is connected to the outflow when connected to the canister. This can immediately kills the unwanted pests in your aquarium.
How do UV sterilizers work?
A germicidal fluorescent lamp is used by a UV sterilizers which can produce light at a wavelength of approximately 254 nanometers. When the water with the bacteria or algae passes over the bulb, it is irradiated with this wavelength. It mutates the DNA as the light penetrates the bacteria or algae, preventing growth of the organism.
Factors that influence the effectiveness of UV sterilizers:
Size and type of organism:
UV radiation is capable of killing algae, viruses, bacteria, and protozoa. But, a higher dose of UV radiation is required for larger organisms, such as protozoa than smaller organisms, such as bacteria. Also, some bacteria are more resistant to UV radiation than others.
Power of bulb:
The wattage of the bulb reflects the amount of UV light produced by the bulb. More UV light will be produced by a higher wattage bulb. UV light is best produced at temperatures of 104 to 110°F. The germicidal fluorescent lamp needs replacement every 6 months as the ability to produce UV light decreases with time.
The UV light will not be effective if it can not penetrate the water. The penetration of UV light will be decreased by higher water turbidity. UV sterilizers should be placed after the biological and mechanical filters so that when the water enters the sterilizer is as clear as possible. As salinity also affects penetration, UV light penetrates freshwater better than saltwater. If the lamp or sleeve is covered by a film or mineral deposit, the light will be partially or totally blocked. So, cleaning of the lamp or sleeve is important. The effectiveness is also affected by the distance of the lamp from the water. UV light only penetrates clear saltwater to a depth of 5mm.
There will be more killing power if the amount of time the water is being exposed to the UV light is longer. As the contact time is influenced by flow rate of the water, slower flow rates increase contact time. The contact time is also affected by the length of the bulb. The water is in contact with the UV light for a longer period of time with a longer bulb. It is impossible to sterilize all the water in the aquarium as the sterilized water constantly mixes with the water in the aquarium when it returns. To sterilized it completely, all the water should be removed, sterilized, and then returned to the aquarium at one time.
Limitations and potentially harmful side effects of UV sterilizers:
- As UV sterilizers can heat the water as it passes through, a chiller is required to keep the aquarium water at the appropriate temperature. This is especially applicable if the unit is larger than necessary for the tank size.
- The flow rate required is so slow that it is somewhat impractical to control parasites on larger aquariums, unless larger systems are used.
- UV light can denature many medication, especially chelated copper treatments. So the sterilizer should be turned off when using medications. The aquarium will have a sudden, lethal concentration of ionic copper as the UV light will break the bond of the chelating agent.