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Atmospheric carbon dioxide levels have increased since the industrial revolution due to the increase in combustion of fossil fuels. These elevated levels of CO2 have been cited as a significant cause of climate change. Hence, there is a well motivated need to find ways to mitigate CO2 emissions. Chemical absorption and geological storage of CO2 have high energy consumption, high capital cost and potential leakage. One possible alternative strategy is the use of microalgae for mitigation of CO2. This paper focuses on the influence of media composition on the growth rate of two microalgae strains, Chlorella vulgaris and Scenedesmus actus. A KNO3 based medium was found to work better for Chlorella, while a urea based equivalent worked better for Scenedesmus. Upon reduction of the urea concentration, the algae growth rate increased slightly, showing that the urea level was not the limiting ingredient in the medium. The urea based media investigated here resulted in growth similar to that found with previously reported KNO3 based media. This should result in an economic benefit in large scale algae cultivation for CO2 mitigation, since urea is typically less expensive than KNO3. Additional media components were tested and it was found that EDTA and vitamin B do not result in a significant increase in algae growth rate.