Filters help to keep clean, healthy water by stopping dirt and algae. To work properly, all the water in the waterfall should go through the filter every 2 hours. The 3 main types of water filters are biological, chemical, and mechanical.
At their nature, biological filters are alike to mechanical filters in those, forced water flows through a filtering agent. The difference is that the filter basis have a colony of live bacteria that consume ammonia and harmful elements, converting them into nitrites and then into nitrates for use again by fish and plants. The system needs on the constant motion of water, and thus oxygen, through the filter to keep bacteria alive.
Usually biological filters are installed outside the basin and can be covered behind plants or stones. A pump must be reliable.
Chemical filtration means using water cleaning agents to attack particular impurities. This method is often used in small waterfall or pond without plants or fish.
Mechanical filters use a straining mechanism to catch dirt in the water. It circulates water through a box containing granules of fuel ash or activated carbon, brushes, foam, or fiber padding. These filters are economical.
But they can clog easily, requiring frequent washing and replacement of the filter components. Most mechanical filters are powered with a pump. Another mechanical option is a pressurized filter. These need regular back flushing and change of sand impurities. This method is often used in small waterfall without plants or fish.
For crystal-clear water, supplement your filtration system with an ultraviolet cleaning. A UV clarifier uses ultraviolet radiation to clean the pool of virtually all algae. Submersible and external units are available. The external ultra-violet clarifier utilize replaceable bulb to control algae, which is the source of “green water” problems.