Abstract: An apparatus for treating water or other liquid comprises outwardly extending front side walls defining an entrance for water to be treated, intermediate inwardly extending side walls, central parallel side walls and outwardly extending rear walls defining an exit for treated water or other liquid. A stepped bottom is integral with and between the side walls. A housing, slidable on the top edges of the side walls, is provided for holding a chemical solution to be dispensed into the water to be treated. A float housing integral with one of the intermediate side walls contains a float which is raised or lowered according to the volume of water flowing between the side walls. A valve on the housing is interconnected with the float whereby the solution within the housing is dispensed into the water or liquid to be treated in proportion to the volume of water flowing between the side walls.