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The following graph demonstrates the relationship between 16 x 30 grade sand and grade 1 AFM® at different flow
velocities. By way of example, if we take a water flow velocity at 30m/hr, sand will remove 30% of all particles down to 5
microns. The sand used was Leighton Buzzard sand from England, which is an exceptionally high quality sand. Other types
of sand are likely to have an inferior performance.
If the flowrate is reduced from 30m/hr to 20m/hr, the 30% reduction is water flow results in more than 100% improvement
in the performance. It is therefore a false economy to operate filters at too high a water flow.
Filtration performance in removal of 5 micron particles at different filtration velocities