Aluminum Sulfate

Aluminum Sulfate (ALUM) is used as a flocculant and combines fine particles causing them to fall to the pool floor, where they can be vacuumed to waste. It is also used in sand filters to help in better filtration. ALUM forms a gelatinous coating which lies on top of the sand and traps tiny particles that would otherwise pass through the filter and return into pool water. 

Active Ingredients: 
Aluminum Sulfate.....99.6%
Inert Ingredients......00.4%