They are mulit functional and work great for keeping your aquarium or pond free from algae and parasites. They have a dual function is this, they kill free floating bacteria, parasites and algae spores as the water passes through the unit.Most units have four main parts, a flow chamber made with Pvc, and internal quartz sleeve, a high intensity U.V. germicidal bulb(which goes in the quartz sleeve) and a transformer of sorts. The light part works like any power compact , the transformer charges the bulb and the bulb radiates. In this case the bulb has metallic ions in it which when charged produce ultraviolet radiation which has a germicidal affect. The bulb is inside the quartz sleeve(If it touches the water directly it will run too cool and not be effective)You use a powerhead or internal filter and pump the water into the pvc chamber and the water flows by the germicidal bulb and it sterlizes the water. Most commercial water systems and the armed forces use this technology to purify water.

Jebo corporation has some new models on the market which are quite economical. The UV h -11,18, and 24 watt units.I was quite skeptical of them until I tested a unit. My saltwater aquarium has ick really bad so I installed a unit-the H-11 on my aquarium. I used a rio 80gh powerhead to run it and in 3 days the ick was gone never to be seen again. I was a believer. Since then I have used them on ponds, saltwater fish, discus etc and they work great.Also another great unit available on ebay is the turbotwist unit, by Esu.



When first installing your U.V. take into consideration the size of the aquarium when deciding on the flow rate of the unit.You want a flow rate of minimum 1x the gallons of your aquarium and maximum 4x the gallons. I.e a sixty gallon minimum flow is 60gh and maximum is 240gh. This will make sure that the effectiveness is not comprimised.Also when first running it run it for a least a week to resolve the problem and then only part time after that.Run them on your aquarium for 3 to 4 days after adding fish to your freshwater or saltwater aquarium or pond, and then periodically for at least 24 hours. U.V sterlizers are a great addition to your aquatic environment to keep up water quality.