It is well understood that water quality and eutrophication are major drivers of harmful algal blooms (HABs). Issues arising from nutrients loads, water circulation, and temperature also encourage blooms of harmful algae, such as Microcystis and Anabaena, in aquaculture ponds. Copper sulfate, an EPA-approved algicide, is often used to treat harmful algal blooms. While effective, repeated annual use of copper can accumulate in aquaculture ponds and potentially make the pond too hazardous for commercial production. Use of alternative herbicides has been proposed however they are less effective than copper. As herbicides have different mechanisms of action, using multiple herbicides simultaneously may be more effective in controlling cyanobacteria blooms. Microcystis aeruginosa and Anabaena spp. were exposed to herbicides commonly used in aquaculture ponds to establish benchmark doses for each chemical. Results demonstrated that both genus’ had comparable dosimetry with some exceptions. Using the effect concentration (EC) where growth was inhibited by 50%, binary chemical mixtures were investigated to determine if herbicide mixtures were more effective than single herbicide use. Herbicide mixtures were designed following the contaminant mixture radial design using EC50 values to represent 1 toxic unit. Five mixtures were prepared based on different ratios of two herbicides (100:0%, 75:25%, 50:50%, 25:75%, and 0:100%) and serial dilutions of each mixture were investigated to determine if herbicides were additive, synergistic, or antagonistic. Results of the study will be used to propose alternative herbicides regimes which may be more effective in controlling harmful cyanobacteria blooms.