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Presently uniform standards for evaluating manure solid-liquid separation unit efficiency do not exist and equipment selection can be based on vague or misleading performance numbers. For example, at first glance, 95% capture (recovery) of solids may look good, but that might change if it were to be discovered that the moisture content of the solids stream was 99% (i.e., liquid separation/removal was poor) or that the solid-liquid slurry tested contained only large fibers (which are easily to remove). To address these problems, (1) separator unit performance should be based on a combined efficiency parameter that takes into account both solids capture efficiency and liquid capture efficiency (e.g., the Worrell-Stessel or Rietema formula) and (2) Characteristics of the slurry used for measuring efficiency should be defined in terms of fiber/particle properties (e.g., particle size distribution, shape, density, stickiness, etc...), fiber/particle concentration, slurry flow rate, and slurry temperature. As a starting point for discussion the following parameter values are offered for consideration: (a) Solids recovery based on three measurements: Total solids, solids larger than 1 m, and solids larger than 100 m; (b) Particle concentrations of 1, 10 and 100 grams/liter; (c) Slurry flow rates of 100 and 1,000 gpm; (d) slurry temperature of 20 C; and (e) Fiber/particle properties that are limited to one or two recipes agreed upon by industry. Alternatively, several recipes could be used based on type of animal and possibly operational factors (e.g., when sand is used for bedding at dairies vs. when sand is not used).