Microbe-Lift CMC (Calcium Montmorillonite Clay) is a powdered clay from one of the highest calcium clay deposits in the world. This calcium montmorillonite clay has a negative electric charge that binds the clay particles to positively charged toxins in the water. This clay is a nutrient source for koi that also polishes your pond water.Nutritional source for KoiClay from highest calcium clay despositsPolishes pond water