UV Sterilization primer

Discussion in 'User-Created Articles' started by jhnrb, Feb 6, 2006.

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  1. jhnrb


    Mar 9, 2005
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    -What is UV Sterilization?

    What exactly is UV sterilization? It's actually a very simple process using ultra violet (UV) light for rendering sterile unwanted free floating bacteria, algae and parasitic organisms, like ich. The UV Sterilizer light affects the living cells by altering the structure of the cell's nuclear material. The end result is the organisms fail to reproduce, eradicating your aquarium or pond water of these unwanted nuisances.

    Functionally, UV sterilization is done by running water in an out of a chamber that contains a UV sterilizer light bulb. The UV sterilizer bulb is usually contained in a glass (quartz) sleeve that is in the shape of a test tube.

    -How are they set up?

    There are two types of UV sterilizer set-ups, the in-line and the hang-on types (some sterilizers can be hooked up both ways). The in-line set-up, usually has the sterilizer under the tank (or beside a pond) in line with a pump and filter (if a mechanical filter is used). Hang-on uv sterilizers have a mechanism for hanging the uv off the back of an aquarium. This is often easier to set-up, but hobbyists often prefer the in-line set-up because it removes the somewhat unsightly piece of equipment from view. You could also hang a hang-on uv from a sump.

    UV sterilizers require a pump with a certain flow rate to run water through them. It is critical that the pump put out a flow rate within the acceptable range of the uv sterilizer. These acceptable flow rates are listed by the manufacturer of the sterilizer in terms of GPH (gallons of flow per hour). The flow rate depends on whether you are using the uv in a pond or aquarium and if you are using the UV to sterilize protozoa or clarify the water (sterilize the algae).

    -How about uv sterilizer safety?

    UV sterilizer light can be damaging to the human eye so DO NOT look into the bulb. Always unplug your unit when working on it to prevent possible shock if it breaks and gets wet.

    -Who needs a uv sterilizer?

    UV Sterilizers are recommended for all saltwater and freshwater aquariums and for ponds.

    -What can be eliminated with a UV sterilizer?

    UV sterilizers will eliminate protozoan parasites such as ich during the new born, free swimming life cycle stage of the parasites. NOTE: They do not eliminate the ich parasites once attached to the fish. UV sterilizers can be used with other methods to treat ich.

    UV sterilizers will eliminate free floating algae. It will not eliminate algae that is stuck to your glass or imbedded in your live rock. It needs to go through the UV sterilizer to be eliminated.

    -Can UV Sterilizers have negative effects?

    Yes. UV can alter the structure of some dissolved chemical compounds. When using any drug or chemical medication check the directions for the drug or chemical to see if you should turn off your UV when using the drug or medication.

    Many aquarists only use the UV at night. There are many free floating beneficial planktonic animals in the water that come out at night that can be killed by a uv sterilizer. Because of this many aquarists only run their uv during the day. You can put it on the same timer as your lighting system.


    UV sterilizer bulbs with four pins at one end should be replaced once a year. Lamps with two pins at each end should be replaced every six months. They will lose intensity over time and after one year the loss in intensity is likely to be critical.

    Depending on how clean the water is going into the UV sterilizer, you may need to clean your UV sterilizer quartz sleeve. If the UV light from the bulb can't penetrate the sleeve, then it won't reach the water that flows around the quartz sleeve. The quartz sleeve can be cleaned with white vinegar.

    -Flow Rates:

    The recommended flow rates and required wattage for tanks may not seem consistent between manufacturers. The Emperor 25 Watt UV Sterilizer is rated for 125 gallons. The Aqua Ultraviolet 25 Watt UV Sterilizer is rated for tanks up to 100 gallons. The Pentair Aquatics 25 Watt UV Sterilizer is rated for 200 gallons. The Coralife 18 Watt for 250 gallons. Some of this may be because the manufacturers are measuring things differently. For Example: Emperor Aquatics' recommended flow rates are based upon when UV Sterilizer lamps are operating at their 60% end of life efficiency. Additionally, flow rates may be comparing apples and oranges because they may be referring to the effective kill rates of different organisms.

    Size pumps in accordance to the manufacturer's recommendations at the upp end for what you want to do. i.e. clarify, or sterilize.
    jhnrb, Feb 6, 2006
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