My mom has a smartpond UV Pond Clarifier (http://goo.gl/JkfoU0) that we bought at Lowe's. I never did get it to work when we bought it last year, and when I went to mess with it this summer, the bulb had gone missing. The same brand sells a 9-watt UV replacement bulb through Lowe's for $11.98. I did a search on Amazon (results: http://goo.gl/MQoJOP) and found much cheaper bulbs, but some of them say UVC or UV1, etc. What is the difference between these different types of bulbs? Can other letter/number models be used? Any help is greatly appreciated!