you can get aqua lights (red, green and blue) from Pet Solutions. they work underwater. I have all three colors, but I found the red light did not collect algae...the green light collected hair algae (I took out the light), the blue light did too but not as bad (still, I took out the light); the red light is in a corner of the tank behind an upside down branch driftwood, I leave it on all the time, it look really cool at night (it is not too bright, so the fish can "sleep" with no problem). black lights probably have no nutritional level, I would stay away from the black lights unless you have cool pictures of Jimi Hendrix and Pink Floyd