I have a sumpless 30. I don't have any problems keeping the sand bed clean. I am not sure why. I have a large brittle star that will rake the sand at night. 30 hermits and a blue devil damsel that is constantly stirring the sand with its tail.
I can't imagine going sumpless on my 180G. How do you use a float switch/valve for top off?
Also, my 55G was sumpless for its first 6 months of life and it looked like R2D2's innards in there. I am so glad to have the display tank look pristine and like a reef, not some scientific experament gone bad.
I have a sumpless 46 gal but do have a 18 x 4 x 12 refugium hanging on the back. I have a Remora skimmer hanging off the refugium which has eliminated all the bubbles that were getting into the tank. The refugium also serves as a settling spot for detritus which can easily be vacuumed out.
