Abstract: An echo chamber including a high-strength, structurally rigid receptacle and a weight bearing grate through which the water from an artificial outdoor waterfall may pass, which grate can support considerable weight loads exerted by materials such as rocks, stones, and the like. The receptacle functions as a substitute for a flexible artificial waterfall water sump liner and receives recirculating water of an artificial waterfall. When constructing a disappearing artificial waterfall using a chamber constructed according to the present invention, rocks or other material are placed on the chamber's grate. As water cascades through the material on the grate and falls into the chamber, an echo sound is generated. Differing configurations of the stones on the grate and changes in water level in the receptacle produce echoes of different pitch and intensity.

Abstract: A fish deterrent device for discouraging fish from passing through a weir opening and into a filtration unit enclosure of an artificial body of water. The device comprises an array of closely-spaced spiked members that project at least in a direction opposite to the direction of water flow through the weir opening. The device may cover either the weir opening or an opening provided in a weir door of the filtration unit enclosure. The spiked members both physically and visually discourage fish of all sizes from entering the weir opening while easily allowing water to pass therethrough.