Abstract: A solid chemical dissolver for making liquid solutions from solid chemicals packed in small containers is disclosed. The solutions are used for cleaning tanks, boilers, cooling towers and similar equipment internally. The dissolver has at least one bowl for receiving and holding one or more of the small containers of solid chemical. A spray nozzle aimed at the solid chemical directs fluid under pressure at the chemical to dissolve some of it and form a cleaning solution. A reservoir is provided to hold the solution prior to use, and a drain member leading away from the reservoir is provided for withdrawing the solution and using it to clean the tanks or other equipment. A fluid level detection switch assembly is disposed in the reservoir to control the amount of fluid from the nozzle and the level of the solution in the reservoir. Various embodiments of the invention are disclosed.