Aluminum Sulfate is a product better known as Alum. Alum is a white powdery flocculent that when circulated in your swimming pool water, quickly clumps all the fine particles in your cloudy water, including green algae, into particles large enough that the green algae sinks down to the bottom of your swimming pool, clarifying your pool water. Then you simply vacuum the bottom of your swimming pool and all the green algae in it to waste.

We do not recommend using Alum in pools that have Cartridge Filters.

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For swimming pools and spas, a Flocculant will attract suspended particles to itself, resulting in marble sized clumps that sink slowly to the bottom of the pool. The filter pump remains off during treatment, and after 8-12 hours a thick white carpet needs to be slowly vacuumed – to waste.

Aluminum Sulfate is a double salt with a strong positive charge. Particulate matter in solution have negative charges. Over the period of several hours, the alum molecule attracts suspended particles. Eventually it grows to a large size and heavy weight, until it slowly sinks to the pool floor. It works best with well balanced pool water, and in water temperatures of at least 70° F. The tricky part of using alum is that the aluminum hydroxide precipitate must be vacuumed to waste the following day. Alum is considered a flocculant, because it sinks material to the floor - as opposed to clarifiers, which enlarge particles only slightly, for trapping within your pool filter.