Megaflow trough valves are float operated valves for use in automatic filling of water troughs. The valve is configured for underwater mounting only. The float is connected to the valve with a nylon cord, this operates a pilot valve, when the water level drops, the pilot valve is opened, and the main diaphragm valve is activated. Megaflow is a good choice where its high flow, compact, robust, non-corrosive construction is beneficial.