In my experience the key factor to using a overflow is to make sure the overflow is sized correctly to the flow your running. Obviously you will have your tank overflow if your running more flow than your overflow can handle, but the thing that most people don't think about is that you will have bubbles get trapped inside your U-tube if your running your overflow to slow. This will cause the overflow to fail eventually and you will not know when. There is not much to worry about if you run correct flow.
I like this style, but regardless of the style you pick the best thing about this one is that he drilled the U-tube section and put a check valve in it, so it's very easy to get it started and if your ever worried about air bubbles in your U-tube you can just suck a little water out and make sure there is no air in the U-tube. http://www.angelfire...IYoverflow.html
Edited by SCreefer, 08 April 2012 - 06:34 AM.