What exactly is UV Sterilization? 
It's actually a very simple process for removing (or filtering) unwanted free floating bacteria and parasitic organisms, like ich, out of your water by passing the water through Ultra Violet (UV) light. The organisms die, erradicating your aquarium water of these unwanted nuisances.

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.

What can I kill with a UV sterilizer?
UV sterilizers will destroy parasites such as Ich during the new born, free swimming life cycle stage. 
NOTE: They do not kill or remove the Ich parasites once attached to the fish. UV Sterilizers can be used with other methods to treat Ich. UV Sterilizers will kill free floating algae. It will not kill algae that is stuck to your glass or imbedded in your live rock. It needs to go through the UV sterilizer to be zapped.

What influences the effectiveness of a UV sterilizer?
1. Wattage. See the "UV Sterilizer Wattage" chart below for general recommended wattages for your differnet sizes of aquariums. (These are some conservative estimates that may differ with the recommendations of the manufacturers. See the Flow Rates at the bottom of the right column for comments about the discrepencies between manufacturers with regards to tank size recommendations.)
2. Contact time. The longer it takes for water to pass the bulb, the greater the contact time. For this reason the longer the uv sterilizer bulb, the better. Also, this is a good reason not to use a pump that more powerful than is recommended--the water will pass the uv sterilizer too quickly to maximize the effectiveness of the UV sterilizer radiation.
3. The Age of the Bulb. The uv sterilizer bulbs need to be replaced every six months.
4. Light Blockage. The uv sterilizer bulbs are contained in quartz sleeves. These sleeves will need to be cleaned periodically to prevent light blackage.

Can UV Sterilizers have negative effects?
Yes. UV can alter the structure of some dissolved chemical compounds, so you do not want to run your UV sterilizer when treating your aquarium with any drug or chemical medication. 

Depending on the cleanliness of the water going into the uv sterilizer, you may need to clean your uv sterilizer more or less often than someone else. Specifically, the outside of the quartz tube that the bulb is set in is what needs to be cleaned. 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.