The UV Sterilizer: Friend or Foe
by Michael G. Livadas
Are you tired of marine fish deaths, constant water changes caused by medicinal treatments, algae blooms, and common saltwater diseases? What can an aquarist do to battle these menacing and frustrating experiences? Well, this article will address these issues and more by discussing a helpful, yet slightly complex piece of machinery called the Ultra Violet Sterilizer.
The UV sterilizer is a tool used by many marine aquarists to combat and kill harmful, waterborne bacteria, viruses, fungi, and small protozoans, which may turn a beautiful and peaceful aquarium into a deadly nightmare. The UV unit also helps control algae blooms by killing waterborne algae. My introduction to the UV sterilizer derived from a challenging battle with a common marine fish disease called Cryptocaryon (ICH). After analyzing my unfortunate situation, I concluded many variables (overstocking, filter maintenance, new fish introductions, etc.) to the cause of my dilemma. The problem and its causes were eventually resolved; however, fish lives were lost. To a true marine aquarist, a lost fish symbolizes failure and an opportunity for improvement. I consulted a local reliable pet store for techniques on how to avoid common marine fish diseases. The UV sterilizer was mentioned during the inquiry, but initially discounted because of cost (15 watt - $119). I researched my options and eventually concluded that the UV sterilizer would help me provide superior water conditions for my marine aquarium inhabitants.
The UV sterilizer was rushed home and immediately hooked up to my Fluval 403 canister filter. I witnessed positive results in only 48 hours of the initial hook up. My marine aquarium water looked flawless - crystal clear. My yellow tang (zebrasoma flavescens), once light yellow, turned bright yellow. The other tankmates looked rejuvenated and lively. I immediately thought to myself, "Gee that UV sterilizer is the best thing since sliced bread. My marine fish headaches are over." Well, yes and no. Yes, the UV sterilizer has provided months of clear and somewhat safe water conditions for my marine inhabitants, but after six months I have to take apart the whole unit and change the bulb and clean it! The disease headache turned into a cleaning headache. The UV bulb loses its effectiveness -kill ratio- after six months and must be replaced. Due to its exposure to water, biological slime builds up on the bulb surface, which greatly reduces the efficiency of the unit.
The "kill" efficiency of the UV sterilizer depends upon several variables listed below:The available energy (wattage) of the bulb (4, 8, 15, 30 and 50 watts). · Age of the bulb (greater than 6 months). · The species and individual characteristics (age and size) of the microorganisms.
Temperature of the bulb and system (106 degrees F). · Distance between the bulb and the target organism - (2 inches).
Presence of slime and other biological or mineral deposits on the bulb surface. · Duration and intensity of exposure, flow rate of water through the unit (25 to 30 gallons per hour per watt).
Placement of the unit. Connect the unit to the end of the filter line, before the water returns to the tank. This will provide maximum sterilization.
Aside from the above variables, there are some more factors to be aware of when utilizing the UV unit. When changing the bulb, never look directly at the light when the unit is turned on. This may cause permanent damage to eye tissue. Also, always unplug the unit prior to cleanings and to water changes. The bulb will heat up if it is in operation in air instead of water. If the unit is submerged in water while it is still hot after or during operation in air, it may break and release electrodes in the water. This could be a highly shocking experience!
Overall, the UV sterilizer is helping me to maintain a healthy and happy environment for my marine inhabitants by killing most harmful microorganisms. The UV unit may be frustrating during maintenance, but then again so are fish deaths. Keep in mind the factors required for success, and make sure to use caution when handling the unit. Remember to consult your local pet stores when deciding on types of UV sterilizers. Marine fish keeping can be a rewarding experience when success is achieved, and the UV sterilizer can help the true marine aquarist reach a consistent level of success.
Moe Jr., Martin A. The Marine Aquarian Reference: Systems and Invertebrates (Plantation, Florida: Green Turtle Publications, 1989).
Stratton, Richard F. The Marine Aquarium Yearbook ( Neptune, New Jersey: Yearbooks, Inc., 1996).
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