it has a bilt in filter. i love it i took out the bio ball and replaced them with lr rubbal. it even gives you a place to put your heater and protin skimmer. it has a surface skimmer and 2 returns that you can move around. it came with 54w of light 2 leds 2 ways tow control the lights. all you do is add sand water rock and fish then its good to go i am making it in to a coral tank when i get more money. but i think it is one of the best buys yet