This is a great aquarium but I would recommend investing in a small filter system to keep it clean and the undergravel filter is not a filter at all its a plastic bottom with small holes in it. I honestly haven't figured out the use or reason for it. It doesn't seem to be doing anything extra. That being said the colors are very cool all though I am not able to get the green one, the red, blue, yellow, orange, and purple are very nice and cool to look at plus its enough light to see my fish at night but not enough to bother them like a regular light does.