Static and dynamic cultures of Selenastrum capricornutum Printz were optimized and compared for evaluation of toxic chemicals. Pigment analysis, nucleic acid and protein concentrations, and productivity measurements indicated that once growth was optimized, the alga was physiologically similar in both systems. The toxicity of phenol and g-naphthol to S. capricornutum was tested using both static and dynamic systems and results did not differ significantly. Toxicant concentrations were monitored with time throughout the toxicity bioassays. Results demonstrate that growth optimized static algal cultures can be used for hazard assessment without loss of sensitivity.