A new look at an old technology—sand filtration for above-ground pools

By Mitch Smith

Above-ground swimming pools—whether steel-wall, soft-sided, or any other type—all contain water, which needs to be filtered. While most facts about above-ground pool filters have remained constant over the years with respect to the pros and cons of the three basic types (sand, cartridge, or diatomaceous earth [DE]), there are some changes in the market that savvy dealers can use to their advantage.

The general truths are true

No matter the swimming pool type, DE provides the finest filtration, sand is easiest to understand and maintain, and cartridge filtration is in between on both ease-of-maintenance and particle-size scales.

Sand filters

Using sand to filter water dates back to the Roman baths of ancient times. And, while there may be some differences in how their valves operate, or the design of the laterals that hold the sand, today’s sand filters function pretty much as they always have. As water passes through the sand bed, particles are trapped by the sand crystals. When the sand bed has trapped all it can, usually measured by a change in pressure, or if it has been too long between cleanings (cloudy water), the sand bed can be recharged via backwashing. This process essentially involves running water through the filter in reverse, loosening the trapped particles and flushing them to waste. The sand itself typically lasts several years.

Cartridge filters

Cartridge filters have a bit more variety to them in terms of form and function. Basic cartridge filters have inserts made of paper-like material that trap dirt. The cartridges themselves can be rinsed and cleaned for repeated use. The length of time between required cleanings depends on bather load. The same is true of how often the cartridges should be replaced. The replacement cartridge market can be lucrative for pool dealers.

FILTER SYSTEMS
Sand filter systems for soft-sided pools may be the key to closing future sales of more elaborate pools because they offer better filtration than the pump/filter combinations that typically come in the box.Hayward Pool Products Canada—VL series Hayward’s VL Series sand filter systems provide filtration for above-ground pools of all types, including soft-sided varieties. Easily assembled, these above-ground pool sand filters feature an incorporated pump base, tested sand filtration technology, and quiet pump designed to provide trouble-free functionality.         GAME—SandPro series SandPro filtration systems from GAME are available in three sizes, delivering flow rates of 114, 155 and 170 litres per minute (lpm) (30, 41 and 45 gallons per minute [gpm]). The first model introduced was the 0.5-horsepower (hp) system (model #4510), which is now the middle of the line. The flow rate from this filter is adequate for driving a small pool cleaner and incorporates many features of higher price-point sand filters, including a seven-position valve for backwashing and a hair-and-lint trap on the pump’s wet end. SandPro filter systems meet all National Electrical Code (NEC) and other electrical requirements and come with specialty fittings to connect with the proprietary hose sizes that come with most leading brands of soft-sided pools.     Waterway Plastics—TWM-30 series Waterway’s offering in this category includes a 0.5-hp pump, which is available with or without a trap, and a 406-mm (16-in.) sand filter on an integrated equipment pad. The pump/filter combination is rated at 114 lpm (30 gpm) and comes with Intex pool connection fittings, as well as two, 1.8- x 0.45-m (6- x 1.5-ft) hoses with connectors.   Pentair Aquatic Systems—Sand Dollar® series Pentair uses a blow-moulded process to create its one-piece Sand Dollar® filter systems, which have a non-corrosive tank. The pump/filter combination features a six-position 38 mm (1.5 in.) multi-port valve with a self-priming Dynamo® pump in 0.75, 1, or 1.5-hp ratings. The filter is designed to ensure water is exposed to maximum surface area for optimum filtration and efficient backwashing. The pump, constructed with fibreglass-reinforced components, has a large strainer basket, which extends the time between cleanings, and a see-through strainer-pot lid for easy inspection and cleaning.

DE filters

DE filters, on the other hand, are the most complicated of the three types, and also provide the finest filtration. Grids are coated with DE, which catches the undesirable particles as water passes through. When the DE has caught all it can (measured similarly to sand filters via a rise in filter pressure or visual signs of compromised filtration), it must be regenerated. Some DE filters have a backwash-like function in which the DE is bumped and then recoated onto the grids. Other models require backwashing; however, some areas have rules against flushing DE into sewers. Still, the superior water quality achievable with DE makes these filters appealing to pool owners.