Advice please -re: value of UV steralizer

[RuGlu6]

here is very inexpensive UV light, bulbs are available no problem.
If you want to get you water sterilized a lot, run LESS water through the unit.
If your water is not infected and not much algae then you can turn it off or have more flow through.

http://www.aquatraders.com/category-s/8.htm

(External Hang-On or In-Line Installation.

When using at the proper flow rates, UV Sterilizer can effectively eliminate algae bloom and help control fish disease. Features high quality quartz sleeve maximizing transmission rate, additional hose adapter and mounting kit enhance installation flexibility. Suitable for freshwater, saltwater aquariums, and ponds.)

Also there is one more use that i get from mine.
When there is a seasonal flu, i use it in our bedrooms to sterilize the air, walls and whatever UV light can get to. Its like having your own Sun to sterilize the room. Very effective! Just open the unit and turn it on with out the outer shell to expose the bulb.
Obviously this is done when no one is around and kids are not allowed in these rooms when UV is on. A note on the door is also good idea as a reminder for ourselves.
I usually put it on the light switch operated wall plug so i can just turn it on /off without looking from behind the door.