When I had my Water Dragon I had it in a cage that was 5' long, 2' deep, and 3' high. I used just a regular shop light fixture that was 4' long for his UVB lights. The fixture doesnt really matter, as long as there is nothing blocking the light going into the cage (Like plastic, or glass). The other thing you may watch out for is not setting the bulbs directly on the top. Make sure there is a little space between the bulb and the screen.