For 32 years, the voice of the pool and spa service professional.

One size does not fit all when it comes to filters

By Marcelle Dibrell

Proper water maintenance requires a two-front approach, working in tandem to get the job done effectively. On one front is the chemical treatment, ensuring that the water is free from any disease-causing bacteria. But just as important is the battle waged by the filtration system where particles are removed that could otherwise interfere with the sanitation process. 

Just as sanitizers come in different types and forms, pool owners and service professionals also have options when it comes to filtration devices. As has been true for many years, the three options are cartridge, sand and D.E., and each has its strengths and weaknesses when it comes to filtration performance, maintenance and spatial considerations

In terms of filtration performance, D.E. filter media filters the smallest sized particles, down to about 3 microns. Cartridge filters are slightly less effective at removing the very small stuff, capable of filtering particles of about 10 microns. Meanwhile, sand filters are good for filtering out slightly larger impurities of about 35 microns. 

Filtration performance can make a big difference and we have long noted that there seem to be regional preferences when it comes to filter choices.  For coastal areas where there is a greater need to remove fine debris, a higher percentage of the pools tend to employ D.E filters. 

Analysis of Service Industry News 2015 survey reveals that D.E. filters were reported to be in use on 79 percent of the Southern Californian pools visited by service professionals responding to our survey.

Though they don’t filter particles quite as small as D.E. filters, cartridge filters also come with some advantages, and many people are willing to pay the higher up-front cost to cash in on those returns. For one thing, cartridge filters don’t get backwashed, but rather removed and cleaned or replaced. The ease of maintenance offers one advantage for some. No backwashing also means water savings, making them a little more environmentally friendly. They are also ideal for removing oils and grease. 

Over the years we have consistently found that cartridge filters rank No. 1 in Florida pools, and this year was no different. According to our 2015 Service Industry News Survey, 80 percent of the Florida pools visited by service technicians responding to our survey incorporate a cartridge filter.

For much of the rest of the country, sand filters get the job done as well as it needs to be done. They are fairly low maintenance, requiring an occasional backwash to clean the sand and infrequent sand replacement. They also tend to be the least expensive, and the simplicity of their design means that they can withstand a little more abuse than other filter options.

Service professionals responding to our 2015 survey reported that cartridge filters are used on most of the spas across the country. For pool filtration (see chart), regional trends are more widespread. This is true, in part, because their high surface area is particularly well suited for smaller volumes of water containing relatively large amounts of body oils or lotions. 

In this issue, we will provide basic information about the three basic types of filtration.                                         

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