I had one on my 26 gallon. I thought it was okay. The suction cups never really did seem to stay on the glass(I had to replace them often). When the suction cups came off the wall it would slide above the water, flooding the tank with air. It didn't really skim as much as I thought it would...as the filter part, it did a good job! I also had a HOB filter though. In the end, I was glad to get rid of it!