I have a 40 tall which is the same length as a 30 long if i remember right. I have 2 of them in my canopy, 1 wasnt enough light but that may have something to do with how much depth mine had to penetrate.
Here are some pics of my installation
http://www.aquariumadvice.com/viewto...=753245#753245
They are made by Current USA, and sold at BigAlsOnline as well as some ebay sellers.
http://current-usa.com/lunarlight.html
-Pleco