I would say as long as you have an inch between the top of your tank and the water level you should not have to drop your water level, keep in mind when I say a one inch wave that is actually a 1/2 inch up and 1/2 down from the normal water level. It is not the prettiest edition to your tank but the effects are quite stunning it is about a 4" x 4"x 15" box and it should be located on the long axis of the tank with the least amount of obstructions. Also keep in mind that Tunze projects a 15% to 20% less lifespan of an aquarium with the use of this, and older aquariums that are not constructed well, and also bowfront aquariums are not reccommend do to the added stress. Of course there are mixed opinions on this though.