The surface area of the filter system should be one third to one half of the surface area of your pond. This will important as when your fish grow, and the pond is heavily stocked with fish then the filter will still be able to provide good water quality and so ensure your fish can be maintained in good condition. It is important to know the exact gallonage of your system. The exact volume is important to ensure that dosage of medication can be applied accurately at a later stage. It is also a good idea to know the capacity of your pond and your filter system separately.
Mechanical filtration is the only really filtration.
All the others change the nature of chemicals they come into contact with. Too powerful circulation will prevent the build up of beneficial colony of bacteria by tending to dislodge them. The next stage is a chemical or vegetable filtration Final to polish the water use of sand filter and trickle tower. An overflow is usually incorporated in one of the bays so that the pond water cannot go above a designed level. Figure shows the general layout of a simple 3 bay filter system, and this is what you should aim for.