Two microecosystem protocols, the Standardized Aquatic Microcosm (SAM) method developed by Dr. Frieda Taub and associates (1982) and the Mixed Flask Culture (MFC) method of Dr. John Leffler (1981), were compared on the basis of their response to copper sulfate. These protocols differed in microcosm structure, age, and the variables monitored. Although responses were similar with both systems, the SAM procedure provided considerably more insight into the changes in population densities and nutrient cycling responsible for the observed ecosystem level changes. The SAM protocol was much more labor intensive and required about six times more laboratory effort than did the MFC protocol.