Need minimum of 5 inches of clearance, and you'll have to keep an eye on the salt creep too. VERY LOUD so thats irritating. Was my first skimmer, it does it's job for under 100 dollars, but it needs constant adjustment. I also added a piece of filter pad in the spill tray so there wasn't excess bubbles going back in the tank. Good luck, but my advice is save up for a much better one.