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Filtering down to the finest particle

Filtering down to the finest particle Filtering down to the finest particle

By Marcelle Dibrell

There are three broad options when it comes to pool and spa water filtration: sand, cartridge, and DE. Their ability to filter out small particles is nearly the opposite of their ease of maintenance.

Sand, the cheapest and easiest of the filters to care for, is capable of filtering out only the largest of small particles – down to about 30 microns.

DE, the most expensive and most difficult of the filters to maintain, filters out the smallest particles – down to about 3 microns, and provides exceptionally clean and clear water.

Meanwhile cartridge filters, requiring periodic hose-offs and occasional chemical cleanings, are somewhere between sand and DE on the spectrum of maintenance requirements. They can filter particles down to about 10 microns and are sandwiched between DE and sand in terms of performance.

According to our 2021 Industry Survey, the types of filtration systems employed on pools seems to be a matter of regional preference.

While close to 90 percent of the survey responses of pools on service in Southern California operate with DE filters, that number drops substantially in most other areas of the country, where either sand or cartridge seems to be the preference.

Meanwhile, and as in years’ past, the majority of respondents from the Southeast and Midwest report using sand as the main filtration type.

In the Northeast, Northern California, and Florida regions, cartridge filters dominate.

Only in the Southwest does there seem to be a question of what filter type dominate. Survey participants indicate that their pools are split between DE and sand, and cartridge filters are only slightly less popular. When it comes to filter use on spas, the consensus is to use cartridge filtration. Nationwide survey participants report the majority of spas use cartridge filters. This trend makes sense: hot tubs or spas hold less water compared to pools, making cartridge filters more effective because the filter area is large in comparison to the water volume. And while DE filters work in hot tubs, body oils and lotions can quickly gunk up the filter.

While we are stuck with just these three options for filter types, these days, there are a host of permutations on how to use the filtration media. For example, a layer of DE can be added to the top of a sand filter, and it will noticeably improve water clarity. Similarly, cellulose can be added to a cartridge filter, and the results are surprising.

In fact, nowadays, there are even more options for filtration media, both as filter aids or as total filter media replacements.

Sand can be replaced by a wide array of materials, from the new and high-tech Activated Filter Media, to the fun and fluffy filter balls, to the tried and true ‘Zeolite’. And although these additions may increase the cost of filtration, some of these choices really improve the filter’s performance.

DE can be entirely replaced with Perlite, providing equivalent or better water quality without many of DE’s hassles.

And while there is no true replacement for cartridges, manufacturers have upped the ante with revolutionary new fabrics featuring antimicrobial filtration and specially engineered cores that maximize water flow for greater efficiency and less wear on the pump.

Options abound for filtration media and that is the thrust of this special issue of Service Industry News.

deck had collapsed into the underground garage. She took her two children and fled the building.

Some experts have said that they doubt that a collapse in the pool deck could have resulted in the collapse of the entire building, while others say that it, combined with other factors, may have set off the wider catastrophe. Most agree that the failure occurred at the lower levels of the structure.

It is known that at the time of the building’s collapse, the complex had been preparing for the recertification that state law requires of such buildings in the area that are 40 years old. Major repairs would be necessary to pass inspection, which had not been started prior to the collapse.

Speculation about the collapse has centered on the pool deck area because three years before, engineer Frank P. Morabito was hired by the condominium association to perform an inspection of the building as part of its recertification process. He said that the building, and particularly the pool deck, would require timely and expensive repairs.

Specifically, “The waterproofing below the Pool Deck & Entrance Drive as well as all of the planter waterproofing is beyond it useful life and therefore must be completely removed and replaced. The failed waterproofing is causing major structural damage to the concrete structural slab below these areas. Failure to replace the waterproofing in the near future will cause the extent of the concrete deterioration to expand exponentially.”

He said that the main issue with the building structure and the pool deck also showed damage, with “abundant cracking” in the concrete columns, beams and walls. Although he said the concrete deterioration should “be repaired in a timely fashion,” he did not suggest that the building was under threat of collapse.

Corroborating this report were the findings of an unnamed commercial pool contractor, who visited the building 36 hours before it came down. The contractor was asked to visit the building to put together a bid for cosmetic pool restoration and equipment replacement, which was part of a multimilliondollar restoration project that was just beginning. The contractor told the Miami Herald that while the pool area itself seemed to be in OK shape, the basement garage and the pool equipment room, located under the pool area, were another story. He said he observed cracking concrete and severely corroded rebar under the pool and he was struck by the lack of maintenance in the lower level. After the building’s collapse he said he wondered if this was going on in other parts of the building to cause the collapse.

Particularly troublesome to the contractor was the amount of standing water all over the parking garage.

He mentioned this to a building staff member, who was showing him around. The staff member said that he thought it was waterproofing issues. The staff member also said that they pumped the pool equipment room so frequently that the building had to replace pump motors every two years.

Reports don’t make it clear whether any of the water came from a leaking pool or ocean water, or both of these sources. Similarly, it’s not clear whether all of the water came from overhead or perhaps some came through at a garage entrance or both; however, a Champlain maintenance manager from the late 1990s did say that ocean saltwater would make its way into the underground garage and that “pumps never could keep up with it.”

The question of whether deterioration of the pool area caused or contributed to the collapse will no doubt play a major part in the investigation over the next several months.

The National Institute of Standards and Technology, which investigated the aftermath of September 11, 2001, is sending a team to the Surfside site to make an assessment.

Their findings will likely inform future building codes.

Champlain Towers South in Surfside, Florida. Photo credit:

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