Abstract: A water treatment device for use with cooling towers and heat exchangers includes a pump in fluid communication with the heat exchanger to pump a stream of liquid from the heat exchanger. A hydrocyclone is in fluid communication with the pump and is connected to a collection chamber. A first magnetic liquid treatment unit is in fluid communication with and downstream from the hydrocyclone. A liquid return line is in fluid communication with the first magnetic water treatment unit to permit liquid to flow back to the heat exchanger. A secondary pump is in communication with the collection chamber to pump a stream of liquid and form the secondary circuit. A filter is in fluid communication with the secondary pump while a second magnetic liquid treatment unit is in fluid communication with and downstream from the filter. The secondary pump and filter mechanism is used to filter the heavy solids and particulate matter in the bleed-off or blow-down liquid of the system.