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I am returning to the Fluoride subteam this semester. This semester we have further modified the bottom geometry of the floc blanket reactors so that regardless of concentrations in the reactor, settling will not occur at the base. The design utilizes a flat, sloped plane to minimize the convergence of flocs which in the past caused buildup in the base on the reactors. We also began testing the system with low red dye to PACl ratios because, in the field, arsenic and fluoride tend to have low concentrations and require higher concentrations of coagulant to be removed. These tests often resulted in blocks of PACl and flocs forming in the middle of the reactor and building up, regardless of recirculation occurring at the base. To resolve this issue, the subteam reintroduced the addition of clay to the influent to reduce the amount of PACl that was sticking together. This produced positive results, and now the team is moving forward with running the system with fluoride instead of red dye so that lower effluent concentrations can be accurately measured with a fluoride electrode and we can begin to quantify the effectiveness of 1 vs. 2 reactors when actually removing fluoride.