A biological filter is a crucial part of your pond filtration system. It may be unseen, but its role is vital in maintaining the quality of your pond water. Once the mechanical filter collects fish waste and debris, biological filter takes over, acting as a guardian to protect your precious fish from harmful substances. Beneficial bacteria play a remarkable role in this process by transforming toxic ammonia (NH3) into nitrite (No2), which can be just as harmful if left unchecked. Nitrite is then converted into the safer nitrate (No3). This natural and efficient process ensures the safety and well-being of your fish. If you want to enhance your biological filter, there are products available to activate it further. Experience the wonders of biological filters and witness the magic they can bring to your pond.