Dissolved oxygen (DO) is a vital parameter in the aquaculture industry. The ongoing health of a population of fingerlings in a tank is determined by optimum oxygen saturation levels. Envirosensors can supply a range of galvanic cell dissolved oxygen sensors designed specifically for this application. Another application for residual dissolved oxygen is in modern biological nutrient reduction (BNR) reactors in waste water treatment plants. Here both traditional galvanic sensors or the new generation fluorescence (optical) sensors are used. Dissolved oxygen sensors are available from leading manufacturers like Sensorex Inc, WTW GmbH and Jenco Instruments Ltd. Centrally located in Sydney, Envirosensors is able to service customers Australia-wide.