i am running my current tank (250 gallon) skimmerless and sumpless. i have and extremely deep sand bed and lots of macroalgae growing in the tank. the only drawback i have seen so far is the film that forms on the surface of the water. i do small (5 gallon) water changes twice a week, and use a container to dip the water out of the tank at the surface to get rid of the film.