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Swimming Pools |
Swimming Pool Pump and Motor
The Swimming Pool Surface Skimmer
The Swimming Pool Piping and Plumbing
The Swimming Pool Activating the Water
Heating the Swimming Pool
Type of Swimming Pool Heaters
The Swimming Pool Energy-Saving Suggestions
Swimming Pool Automatic Controls Accessories
Which Type of Filter for You?For residential swimming pools there are three types of filters – high-rate sand, pressure diatomaceous earth (D.E.), and cartridge. Local code requirements will often determine the filter for your pool.High-Rate Sand Filters Now the most popular for swimming pools, these filters are pressure vessels of fiberglass, stainless steel, or plastic with a system of drain and water distribution that maintains a nonturbulent flow through the filtering media. The media consist of special grades of sand, which, if maintained properly, will last for several years. Your filter supplier will recommend the proper sand for your unit.The high-rate filter is based on the concept that high flow rates and pressures drive dirt particles into the sand bed, making maximum use of the filtering media. Theoretically, if the filter were not backwashed, the dirt particles could reach the drain in the bottom and be returned to the pool. Actually, the pressure increase would stop the pump first. The pressure can be monitored on a gauge to determine when the filter should be backwashed. Some 190 to 750 liters of water, depending on the filter's size, is used during the backwash and must be disposed of. If your community prohibits the dumping of this water into the street, storm drain, or sewer system, you'll need a dry well to retain the water until it seeps into the ground. Many manufacturers supply a complete filter, pump, and motor system pre-assembled and ready to connect to the recirculating piping and electrical supply. Pressure Diatomaceous Earth (D.E.) Filters The next most popular after high-rate sand filters are D.E. Filters, which offer the advantages of being more compact, filtering out smaller particles, and requiring less water for backwashing than the sand filters.The D.E. filters strains water through diatomaceous earth, a sedimentary rock composed of microscopic fossil skeletons of the diatom, a small water animal. The skeletons have a highly porous structure of silica which makes them inert to most chemical action. The filtering is through a thin layer of D.E., which coats cloth-like membranes and then crushed, washed, sized, and packed as a white, chalky powder. The coarser sizes are more adaptable to pool filtration; the particular size best suited to your filter will be recommended by the manufacturer. Disposing of the water after backwashing can be a problem if the use of sewers and storm drains is prohibited, as the D.E. Will clog dry wells. Many D.E. Filter systems come with separation tanks that hold about 285 liter of the backwash water while the D.E. Settles into a cloth filter. Then the water is returned to the pool and the D.E. Is discarded. Cartridge filtersGaining quickly in popularity, the new cartridge filters are easy to remove and clean. Even though they must be replaced from time to time, the cost is low. A cartridge's life span is determined by the pool's use and environment. The more dirt that gets into your pool, the more often you'll have to replace the cartridge.You'll need an extra set of cartridges for starting up a concrete pool. The residual plaster can be removed from the cartridges only by an acid wash. Most people will find it more convenient to throw them out and install new ones. The major drawback of cartridge filters is that they do not consistently filter out the smaller particles. |
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