About Biological filtration

Biological filtration refers to the breeding of beneficial bacteria inside the biological filtration media in the filter tank. The beneficial bacteria can efficiently convert the ammonia to nitrites, and then to less harmful nitrate.

About Physical filtration

When water passes through the filter tank, the large particles will be trapped by the biological filter media. The small particle will also be blocked by the linked biological filter media. After a certain period of time, those particles will be accumulated and the pressure in the tank will increase. In order to clear the particles and release the tank pressure, a backwash process of the filter is needed.