Aluminum sulfate has also been used to help control algae growth in ponds, lakes and waterways. Gardeners also use this acidic compound with plants to adjust the pH level particularly basic soil. It has also been used in firefighting foam, deodorant, baking soda, leather making, fertilizer, soaps, drugs and chemical catalysts. Aluminum sulfate is widely used industrial chemical, that is best known for it’s use as a primary coagulant in water treatment.