I'm pretty sure the Tunze has to be out of the water too... It needs air to "surge". I PM'd the Tunze people because I have a lip around my tank and was concerned about this since I do not have enough room to have it out of the water. I only have 1/2" and I think the Tunze wavebox needs 1" or more. The wavebox is also reccommended for a longer tank. Having a shorter tank will make the waves be a lot higher (more splash if ur not careful) It is also better to have an overflow on either end or a center overflow because with just one on the end, the overflow gets starved of water for a few secs and then gets flooded in a few secs.... I did a lot of research on the wavebox and like it (tank is too short tho), but if you go with 2 streams and the multicontroller, the same effect can essentially be reached (if you don't have a large enough tank)