Cartidge filter elements replacement time

Hello everybody,

As all of us know, cartridge filters are used for RO membranes protection. It is a general rule that used cartridge elements shall be replaced when the differential pressure of filter reaches a certain amount, about 0.7 bar for instance. On the other hand, some feed water sources are that clean that it might take about one year or more to reach a predetermined limit.

I ask all to share their experiences or idea about if there are no time limitations for elements to be replaced.