Ferric Alum Slab In Chennai Ferric Alum Slab Near By #Chennai #Madhavaram #Poonamalle #Ambattur #Tambaram #Tamilnadu Slabs: Typically sold as solid, heavy blocks weighing around 20 kg to 25 kg.Usage: Operators usually dissolve these solid slabs in water to make a liquid solution before adding them to treatment tank