Eutrophication poses threats to aquatic ecosystems, necessitating effective mitigation methods. This study has evaluated the efficacy of aluminium treatment in reducing eutrophication under acidic conditions in various water bodies using spectrophotometry and gravimetry. Results indicate a correlation between increased precipitation mass and reduced orthophosphate levels at higher pH. This correlation is due to pH-dependent equilibrium reactions. Acidification below pH 5.7 would negatively impact aluminium treatment effectiveness and pose risks to aquatic biota. This project provides a deeper understanding of the relationship between pH and aluminium treatment, and it can help to avoid and reduce environmental consequences, such as global warming, nutrient pollution, and acidification.