Constructed treatment wetlands are a relatively low-cost alternative used for tertiary treatment of nutrients prior to discharge into receiving water bodies. Phosphorus (P) removal capacity of these wetlands may decline over time, as P is released from the accrued organic soils. Little research has been done on methods to restore treatment capacity of older constructed wetlands. One way is to add amendments containing aluminum (Al) to soil. Intact wetland soil cores were dosed with alum and three other Al-containing alternatives (alum residual, polyaluminum chloride (PAC), and partially-neutralized aluminum chloride (PNAS) under anaerobic conditions. The amendments were applied at three dosage rates; (35.97 g Al m^-2 , 17.99 g Al m^-2, and 8.99 g Al m^-2). The water column pH of the cores treated with alum was significantly lower than all other treatments averaging 3.65 ± 1.12, while the cores treated with PAC (4.85 ± 0.96) and PNAS (4.21 ± 0.93) had pH values significantly lower than the alum residual and controls averaging 6.12 ± 0.19 and 6.09 ± 0.25, respectively. Inversely related to pH, the alum (12.6 mg L-1) and PNAS (9.32 mg L^-1) treated cores had significantly higher water column soluble Al than the PAC, alum residual, and control cores. The DRP uptake rates of all treatments (-60.41 mg m^-2 d^-1 to -2.11 mg m^-2 d^-1) were equal or greater than the release rates of the controls (2.27 mg m^-2 d^-1) suggesting any of these rate might prevent re-release of P from soil in the short term. At all dosage rates, the alum, PAC, and PNAS were more effective at binding P than the alum residual. This research suggests that application of an Al-containing amendment might prevent re-release of P from wetland soil back into the water column but studies are needed to determine efficacy over the long term.