Ultraviolet (UV) sterilization is widely used in aquaculture for disinfection due to its effectiveness and ease of use. UV light is a natural component of the electromagnetic radiation emitted by the sun. Living organisms absorb UV light and within seconds, the light triggers a reaction in the organisms’ DNA that prevents them from multiplying. Using UV light as a sterilizer helps keep disease-causing organisms in the water column in check and reduces the risk of cross contamination among tanks.
The effectiveness of UV sterlization depends on the UV dose, or the time and intensity the organism is exposed to in the UV housing. An effective UV dose is pathogen- or target organism-specific and is directly correlated to water flow rate, and the % transmission of UV light through the water. The higher the % transmission of UV light, the higher the UV dose. UV is especially useful in RAS (Recirculating Aquaculture Systems), because UV treatment only takes place within the UV housing, leaving no residual to come in contact with the animals in the system. Although UV sterilization is simple, it still requires maintenance to ensure the UV is working as efficiently as possible.
UV output from a UV lamp diminishes over time. Pentair AES recommends that the UV lamps be changed after 12 months of operation and that quartz sleeves be inspected and cleaned on a regular basis (every 12 months) to ensure that the transmission of UV light into the water column is not inhibited. If the UV sterilizer is ever shut down for an extended period of time and water is left in the housing, the quartz sleeve should be inspected for bacterial growth and cleaned, if necessary.
Wear gloves while doing UV maintenance. Oils from your hands will inhibit UV light transmittance through the lamp and quartz sleeves. To change the lamp, make sure the power is off to the unit. Next, unscrew the cord grip and pull the lamp out where it can be unplugged. Slide the new lamp into the quartz sleeve and plug it in. To clean the quartz sleeves you will need to drain the water from the UV housing as well as remove the lamp. Ideally, there should be a bypass around the UV so you do not need to shut the pumps off for maintenance.
After the lamp is removed, loosen the retaining nut and remove the quartz sleeve from the housing. Wipe the sleeve clean using a delicate task wipe to prevent scratching. If the sleeves are too fouled or broken, replace with new sleeves as needed. Before putting the retaining nut back on, make sure the O-ring is over the quartz sleeve. This will provide the seal to prevent water from entering the quartz sleeve and damaging the lamp. These are two simple steps that will ensure your UV Sterilizer is operating effectively.
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