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However, one rule of thumb that may be used under lower temperatures and incoming tubidity levels can be to rely on the PAC (Polyaluminum Chloride) dosage use by the Cornell Water Filtration Plant Plant Operators. According to the active ingredients for the alum and PAC along with the equivalent ratios given for both coagulants, 1 ppm of PAC is approxmately equal to 0.8 182 mg/L of alum. This leads to an optimum dosage of approximately 4.0 mg/L of alum for the Pilot Plant Flocculator. Note that this may only apply for low temperatures and incoming tubidities.