The aim of the project was to measure the BOD of various species of algae alone and in association with bacteria under incubation conditions of 5 days' time in the dark and at a temperature of 20 C to determine if algae have an effect on BOD measurements under the standard conditions. The culture procedures used to supply Chlorella for the BOD tests are described and the growth rates of this alga in four different media were measured. Because there is little information in the literature on the measurement of dissolved oxygen (DO) in the presence of algae, tests were carried out to observe if algae affected this measurement. Another series of tests were made to determine if the algae used in BOD tests under the standard conditions would survive the 5 days of darkness in the presence of bacteria.