Sediment filter ares used to remove particles from water. They are rated by a “micron” number. This refers to the particle size that will be trapped by the filter.
These filters are often rated 10, 5, 1 and even 0.5 micron.That s why, which filter is best or how can we choose appropriate one? The smaller the number, the smaller the particulate removed from the water. It seems logical at first to use the smallest micron filter to remove the most amount of particulate. However, this is not always good in filter for several reasons. First, the filters could plug quickly and you will need to replace the cartridges often. In addition, a plugged or restrictive cartridge means not as much water flows to the membrane and the membrane needs adequate water pressure to function properly. For this reason, most RO Membrane manufacturers recommend a maximum of 5 micron rating for the water supply to allow the RO Membrane to do its job properly. This is typically done with filter cartridges using at least 5 microns for first stage filtration on the RO units.
Some water purifier devices have 5 microns and 1 micron filter. If you have this device you don't need to think to choose sediment filter.
If you have a reverse osmosis drinking water unit, 5 micron filtration is the normal for the sediment prefilter. There's no reason to use a tighter cartridge, and it might cut pressure to the membrane and have negative results.