Mechanical filter
Removes suspended particles from the water: debris, uneaten food, plant residues. It makes the water clear and protects the biological filter.
Detailed explanation
Mechanical filtration is the first stage in any filtration system. The water passes through materials such as sponges, synthetic wool or filter socks that retain solid particles.
In external canister filters, the mechanical sponge must always be positioned as the first layer, so that the water passes through it before reaching the biological material. This protects the ceramic rings from clogging.
The filter sock is widely used in marine aquariums. It is positioned where the water enters the sump and captures the coarser debris. It must be changed or washed every 2-3 days otherwise it becomes a producer of nitrates because the trapped debris decomposes.
Mechanical sponges exist in different porosities. It starts from a coarse sponge (large pores) to a fine one. It is not advisable to use only very fine sponges because they clog quickly, reducing the flow.
Synthetic filter wool is economical and very effective at making water crystal clear but must be replaced regularly. It should not be reused for too long because it loses its filtering capacity.
In ponds, filter mats of various thicknesses are often used in the filter chambers, or vortex systems that use gravity to separate the heavier particles.