Diatomaceous earth filters
Unlike sand filters, frequently backwashing DE filters does not affect the filtration rate. However, it does create extra work and expense for service techs. Similar to sand filters, DE media should be backwashed for three minutes; however, the procedure should be broken down into a one-minute backwash, followed by one minute of filtration for three separate cycles (the pump should be shut off each time the tech switches between modes). This procedure helps separate the DE coating from the grids, allowing it to be removed from the filter.
A DE filter should be backwashed at the same 69 kPa (10 psi) increase over normal operating pressure as any other filter media. These filters should be torn down, cleaned, and degreased by a service tech at least twice a year. Body lotions and sunscreen collect on the grid material, and simply backwashing the filter will not remove these films. That said, it is also recommended service techs use a degreasing agent to complete the filter maintenance process. Technicians should also note: muriatic acid will permanently lock the oils and lotions into the grid material and, therefore, it is not recommended.
When recharging the DE filter, one should always follow the manufacturer’s recommendation as to the amount that should be used to charge the filter. The proper way for a technician to do this is to use a 19-L (5-gal) bucket to mix the water and DE together to create a slurry. Then, the slurry should be poured slowly into the skimmer while the pump is running. This will ensure the grids or elements are properly coated from top to bottom.
Cartridge filters
Cartridge filters are not designed to withstand water flow in a reverse direction; therefore, it must be taken apart to clean. The process is completed in the same manner as a DE filter teardown—hosing the surface debris off the cartridge is the first step.
Body oils and lotions are the number one contributor to a plugged cartridge filter. The oily buildup on the surface plugs the pores on the cartridge, which restricts water flow. It also creates a very sticky surface. Therefore, getting this debris off the cartridge surface is the difference between frequent media replacement and those cartridges that last a long time between cleanings.
Cartridge filters trap dirt on the surface. When the filter is turned off, the debris falls to the bottom of the tank to free up more surface area for the next cycle. If the surface of the cartridge is sticky, the debris does not fall away. Instead, it can plug up the filter rather quickly.
Many pool professionals now offer winterizing cartridge filter cleaning services. When performing this service, technicians not only hose off the filter, but also soak it with muriatic acid and a filter cleaning agent, then re-soak it with a liquid chlorine bath to brighten and lighten the filter (making them look nicer when returned to the client). The filters should be allowed to air dry before they are used again.
“We like to remove cartridge filters when we close the pool because temperatures fluctuate throughout the winter and early spring, causing mould can develop in the media which is very hard to remove,” says Huston.
Joe Koch with Blue Wave Pools in New Jersey says his company performs an enzyme wash and acid dip on DE and cartridge filters.
“When we winterize a pool we perform a general cleaning of the filter. At this time we determine how dirty the filter is and whether or not the media can be cleaned with a hose-off alone,” says Koch. “If further cleaning is necessary, we take the filters back to the shop for deep cleaning.
Koch’s team starts by soaking the filters in an enzyme wash overnight to break down all of the organics on the filter. The next morning, they perform an ‘acid dip,’ which removes all of the minerals.
“This process makes the filter cartridge look like new every time,” says Koch. “This is a great money-making service that keeps our guys busy in the winter. After we clean the filters, we bring them back to the customer during the winter to re-install them. During this visit, we also take the opportunity to check on their pool and winter cover.
“This gives us an extra visit with our customer to talk about other opportunities for upgrades for the following spring,” says Koch. “It’s always good to remain in contact with customers over the course of the winter.”
Mike Fowler is a commercial sales manager for Pentair in Sanford, N.C. He has been with the company since 1992, starting his career in the technical services department at Purex Pool Products. Fowler has held many managerial roles within the company, including marketing, trade show manager, and account manager. He can be reached via email at mike.fowler@pentair.com.
