Dissolved oxygen (DO) is one of the most important indicators of water quality. It is essential for the survival of fish and other aquatic organisms and is used in hydroponics as well. When dissolved oxygen becomes too low, fish and other aquatic organisms cannot survive. Sper Scientific dissolved oxygen meters are made to accommodate the user with rugged, portable meters for use out in the field. All of our DO meters offer fast and accurate DO response times in wastewater, surface water and aquaculture applications. Three basic styles of DO meters are available for varying applications: Pens, Portable Meters, and Multi-parameter meters.