Mechanical Pond Filtration: Refers to the physical removal of debris from water by materials that trap large and small particles. This is done by flowing water through a cartridge that traps the dirt. The cartridge is then periodically cleaned. Cartridges are rated in terms of hole size in the material. Polyester Pre-Filter Pads last longer and filter better that other pre-filtration products, even after several cleanings.
Heavy solids, flowing by gravity, can settle out from the water flow in a large settling tank. The quantity of solids settling is dependent on the flow rate and contact time within the settling tank. Large settling tanks with slow flow rates work best. Centrifugal force cone tanks can settle more solids in a smaller space if flow rate is correct. I must mention at this point that the drain pipes themselves can act as settling area if the flow rate is slow enough. Settling tanks and the drain pipes must be flushed frequently to rid the system of heavy waste. Drain pipes can be flushed after the settling tank is drained and a pressure differential exists between the pond water level and the drain pipes.
Not all solids will settle out; usually a secondary form of mechanical entrapment must be used. This secondary mechanical entrapment can be filter brushes or polymat type material. These materials are positioned in a way which the water flow cannot bypass.
Water flow and debris will find the path of least resistance and flow around the mechanical filter if possible. The material used in mechanical entrapment must not have a tendency to plug up quickly.
A course grade material (brushes or enkamat) will trap medium large solids but not restrict the flow of water. Finer particles which pass through should be removed in sequence by a finer media (polymat or foam).
The entrapment of solids is effectively spread out gradually. This reduces the tendency of the filter to plug up to quickly. All mechanical filters should be flushed frequently to rid the pond or organic waste. Essentially, most of the solid waste should be removed before it reaches the biofilter.
Mechanical pond filters list the filtration size in terms of microns. The larger the micron size the less will be trapped by the filter. Typically, pond filters have micron sizes from 50 to 100 microns. Keep in mind that the smaller the micron-size the more quickly the filter will clog and need to be cleaned.
All ponds should have a mechanical filter.
Mechanical pond filters simply remove solids from the pond by straining water through gravel, brushes or foam filters.
Mechanical pond filters can be fitted directly onto a Submersible pond pump and are suitable for small ponds with only a moderate fish population. Regular cleaning is normally required to keep them working properly (about once a week in the height of summer) though self-cleaning models are also available. The mechanical pond filter is effective the moment it is switched on, unlike the biological filters.