Tantora White Mineral Stones 100g Pack Natural Montmorillonite Absorbs harmful chemicals and improves water quality Enhances the natural colour of shrimp & fish, especially whiteness Aids the shedding process for shrimp Contain beneficial minerals How to use: Use 100g of stones per 50-60 Litres To prevent the stones cracking or breaking in the tank, first soak them under water for a short time - do this a few times over a few minutes Remove/Replace after 6 months