WHEN: Use when pond water is murky. WHY: Keeps water clean, clear and healthy by reducing organic loads in the water. Naturally promotes a healthy aquatic environment. Blend of beneficial bacteria, enzymes, and natural barley. Breaks down fish waste, phosphates, nitrates, and other water pollutants 4 tablets per pack. Each tablet works for up to 2 weeks. Treats up to 800 gallons of water.