The most important issues, which should be taken into consideration while choosing a sand filter, are the surface where water touches the sand and the height of the sand in the filter.
The flow rate of water increases in a filter whose hub is wide and the upper side is narrow.
In addition, if the height is low, the large hub diameter of the filter is of no importance.
In order for the particles to be kept in the filter, the flow rate of water should be minimized as much as possible.
Slow rate and high sand level are sine qua non conditions for fine filtration. For example, in a conical filter whose hub is Ø1600 mm and upper side is Ø800 mm, while the rate in the wide section is 50 m³/h, it will be 100 m³/h in the upper section.
Particles can not be kept at this rate and the dirt accumulated in the upper section is pushed to the sand ground.
A significant pressure is formed against the water flow and the flow rate decreases significantly, and the water circulation time needed for the pool increases.
It will be a more accurate approach to deem such a filter as a filter of Ø800mm.
It is a known fact that the said conical filter is not accepted in any of the developed countries and it is a non - standard product.