Abstract: Composition and method for treating fluids with select facultative organisms and/or nutrients. At least one facultative organism is selected and added to a fluid to stimulate/facilitate biological remediation of the fluid. In one embodiment, the select facultative organisms are put into frac pits/ponds containing frac water to inhibit the sulfate reducing bacteria in the frac water. In another embodiment, at least one facultative organism and nutrients are selected and added to a fluid.