I have a 3 gallon, 9.25" long x 8" wide x 8" height and my light is a Finnex Planted + 10" cliplight, 7000k, 4 watts, 1.33 watts per gallon. The light sits 4.5 inches from the water's surface, and 14" from the bottom of the tank. Depending on where I read, the light is good for medium light...