Dear Hakeem, You have ...

  Dear Hakeem, You have proposed a rather vague question with no additional information. What are you filtering out, sand, iron, other? The pre-filters are there to protect the membrane from damage or fouling. The kind of debris the filters remove, the volume of debris, and the volume of water passing through those filters are all variables. You should be able to define a filter change schedule to meet your particular needs, as every system and its supply water are different!  There are different types of filter medias, mesh, and micron sized cartridges, bags, and spin down filters available. But more information is needed to make any recommendations!