An Inexpensive Aquarium Pump Water Recirculator for the Teaching Laboratory

The design and operation of a simple and inexpensive water recirculator is described, which can replace wasteful running water "tap-to-drain" applications such as providing cooling to Liebig-type (water jacket) condensers. The recirculator uses an inexpensive and easily acquired aquarium pump placed within a large plastic jar or bucket. Data is provided for the estimated water saved per hour when using the recirculator instead of running treated municipal water through the condenser and into the sewer system. An evaluation is provided for the conditions under which the system can operate unattended and when it may be necessary to add ice to keep the recirculating water cold enough to prevent solvent evaporation. The described water recirculator has been used successfully to replace conventional tap-to-drain cooling for Liebig-type condensers in undergraduate experiments carried out by over 300 students over four years.