Reaction of aluminum sulfate in water I dissolved aluminum sulfate in DI water and expected to see just a clear water solution with aluminum sulfate dissolved as ions. However, a precipitate was visible. I addd only 0.6g of Aluminum sulfate so there is no way that the precipitated is saturated aluminum sulfate. Furthermore, it does not seen to be aluminum hydroxide, so then what is the precipitate? Aluminum sulfate has the property of filtering out impurities in water, however, I am using DI water so then what is the precipitate? 

Also, the precipitate is not aluminum hydroxide because aluminum hydroxide is dissolvable in sulfuric acid; however, when I added sulfuric acid to the precipitate solution, the precipitate did not disappear.
According to Wikipedia, "When dissolved in a large amount of neutral or slightly alkaline water, aluminium sulfate produces a gelatinous precipitate of aluminium hydroxide, Al(OH)3."