How to Select a Filter Cartridge for Whole House Sediment Removal
Cartridge filters have the advantage of being low cost, easy to install, use no electricity, and generate no wastewater.
However, the disadvantages of cartridge filters are that eventually, sediment will plug up the Water Filter Cartridge membrane's pores, cause pressure drop, and result in a loss of water pressure in the home or business.
Cartridge filters, however, are easy to change and, in the case of some pleated cartridges, are easy to clean and re-use.
Cartridge filters for sediment removal come in many sizes and types but generally fall into two kinds: Surface Filter Cartridges and Depth Filter Cartridges.
Cartridge filters are often installed in series with a larger micron-rated cartridge filter first, followed by smaller micron-rated filters, down to 1 micron.
Surface Filter (Pleated) Cartridges
Filtration with surface filters takes place only on the surface of the filter membrane.
Sheets of polypropylene, nylon or Teflon, etc., are pleated and bonded on ends to provide a high filtration area. The contaminants are trapped on the sheet's surface, forming a layer that will eventually aid filtration in itself.
As the pressure drop increases, the filter cartridge can be removed from the filter housing and washed off at some point.
One advantage of surface filters is they can be washed off, and the cartridge can be reused.
While pleated filters are often used as coarse pre-filters, usually in the range of 30 – 500 microns, they can also be used in sub-micron applications. They provide finer and consistent filtration due to their definable pore size and structure.
Filtration ratings for pleated surface filter cartridges can be anywhere between 50-micron down to 0.04-micron absolute, generally used in semiconductors or pharmaceutical water filtration.
Compared to a depth filter, a surface (pleated) filter will have a much higher filtration area to compensate for the absence of depth. Filtration areas can go as high as 11 square feet in a regular 10″ x 2.5″ cartridge or higher.
Depth Filter Cartridges
Depth filters are commonly seen as wound string, spun, or “melt-blown” cartridges that trap particles of larger size on the surface and smaller particles under the surface down to the center core.
They work best when a variety of particle sizes are being filtered. Depth filters remove more sediment and hold more sediment in general, without losing pressure, than a surface filter cartridge.
How Small is A Micron?
Filter cartridges for sediment removal are rated in microns. A micron rating for a water filter indicates the ability of the filter to remove contaminants by the size of the particles.
A marked “5 microns” filter has some capability in capturing particles as small as 5 microns.
Filter micron ratings for water are usually Nominal or Absolute.
For sediment removal, nominal-rated cartridges are more common.
Absolute ratings are needed to remove Giardia, a type of parasite when it becomes important that the filter cartridge absolutely must be rated at 1 micron.
A. Nominal Micron Rating
NMR usually means the filter can capture a given percentage of particles of the stated size. For example, a filter might have a nominal rating of 90% at 10 microns.
B. Absolute Micron Rating
Absolute Micron Rating or “AMR” is a single pass test obtained by passing fluid-containing glass beads through a flat sheet of filter material. Any beads that pass through are captured and measured. You want an AMR filter for removing parasites and cysts if you are filtering lake or creek (“surface water” or your well water is under the influence of surface water
Which Type of Filter Cartridge is Best?
One advantage of the whole house filter housings is that you can experiment with different water filter cartridges to see what works best for your application.
Generally, we recommend pleated 50-micron filter cartridges followed by a dual grade 25/1 micron depth filter.
For very fine sediment in the range of 1 to 5 microns, we recommend dual-grade depth filters.
Dual grade depth filters start at 50 on the outside and filter down to 5 microns on the inside, which is very effective over a wide range of sediment particles.
Dual grade filter cartridges will remove 2.3 times the amount of sediment that standard spun or string wound filters remove.
For more information on removing sediment from your water, visit our Sediments page on our Water Problems tab.
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