Evolution Aqua Pure Aquarium 50 Ball CounterEvolution Aqua Pure Aquarium 50 Ball Counter contains millions of beneficial bacteria for optimal biological balance. Each ball is packed with millions of beneficial bacteria which will help smooth out Ammonia and Nitrite spikes and keep your pond clean and healthy. The balls will slowly biodegrade as the bacteria is needed. Place the balls directly into your filter media ideally in a small net bag. They can be placed between sponges matting . If you