Many ads show the fogger placed through a hole that has been cut in the screen top and this can be done, but Injust position the tube to where it sits on the screen top and the opening points down. This way the fog just passes through the screen top and into the tank. Works fine this way. Be sure to use distilled water with the fogger so it will last longer, but remember distilled water is only to bebused for foggers and misting.