The use of secondary fiber and rejected pulp as fiber raw material for medium paper is very economical. However, the use of reject pulp results in the breaking or removal of the fiber charge due to highly anionic in the rejected pulp. This research aims to determine the optimum dosage of poly aluminum chloride (PAC) as an anionic trash catcher. The anion trash catcher has the role of reducing the value of particle charge in the rejected pulp. In this study, the following variations were used: blank (without PAC), 1 kg PAC/ton paper, 2 kg PAC/ton paper, 3 kg PAC/ton paper, and 4 kg/T paper. The method is first adding PAC to the pulp and then giving retention aid afterwards. The results of the charge test showed a decreasing charge in the pulp from -789.3 -µeq/L to -44.45 -µeq/L. Paper properties tested include ring crush, corrugated and internal bonding. The best ring crush test value was 15.4 kgF at a PAC dose of 2 kg/ton paper. The medium corrugated test (known as concora test) value was 19.79 KgF at a PAC dose of 4 Kg/ton of paper. The internal bounding value was 167.70 J/m2 at a PAC dose of 3 Kg/T. All of these properties' test results have entered the referenced standard. This research concludes that retention aid works effectively on fiber after adding PAC, which acts as an anionic trash catcher.