I have applied in the last year a total of 3 as absolutely guarantees reliable and effective products against green water. No effect, the water was brown-green. The fish remained invisible. Because of the assessments now bought this product. The problem with me is because of the dosage, I do not know exactly how much water is in my pond. I guess so 2500 to 3000 liters. So I sprinkled and waited 1 week ago, and then again. The water was a little clearer. Now even the rest inside. Then it happened. The water was clearer and clearer, now sees the formerly brown water as fresh water from. Fish and plants have the means well tolerated. Highly Recommended.