Project talk:Aquarium Edge Illumination
From CoMakingSpace Wiki
LED Strips Alternatives
Here you can get cheaper and waterproof LED strips. If you need a receipt then eBay would be another (less) cheap option. (Patrick)
Driver Circuit
What do you want to control with the Arduino? Just the brightness, or also automatic on/off time during the day? For just regulating brightness these things look rather easy to use. (Patrick)