Clear-Water Barley Straw naturally decays in your pond water, releasing enzymes that aid in maintaining water clarity. A safe natural pond treatment to improve water quality which provides a healthier environment for Koi and other fish. Artificial fish ponds typically build up various toxins and organic matter which naturally occur due to the decomposition of fish and organic waster products. The breakdown of these natural pollutants acts to cloud the pond's water. Keep your pond water clean and clear year-round! Clear-Water Barley Straw products are easy to use, safe and attractive. Clear your pond, fountain and fish tank naturally!