Never mind the flow‐rate, feel the surface area!: A Guide to Filter‐Pump Selection

In some respects, it is a pity that the filter‐pump i.e. the combination of a filter with a pump as a single unit, was ever devised. True, it reduces the plumbing of two separate pieces of equipment and the manufacturer sells, in effect, two items where he might otherwise only sell one. But the existence of standard combined filter/pump units has taken away recognition by the user that he should specify not only the average flow‐rate required but also the effective filtering surface area since this directly relates to the frequency at which blocked media must be renewed in order to maintain that flow‐rate.