Our algae removal tablets (boxed) contain copper oxide, activated carbon. It can help slow the spread of algae in a fish tank or pool and make the water clear. It solves algae deposits and helps you replace the water in your aquarium faster. Improve the purity of the water, reduce the odor produced by algae in the water, and prevent algae from damaging fish ponds and tanks. The ingredients are safe and mild and will not affect the fish. The method of use is simple: take an appropriate amount of this product into the water, and after a period of time, let it dissolve until the algae grow. Quickly removes algae, purifies water and keeps it clear.