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2014SumShotcreteEMag

Pool & Recreational Shotcrete Corner (a) Fig. 2: This is one brand of salt that is used— they all work pretty much the same. These are 40 lb (19 kg) bags; residential swimming pools typically need 25 to 30 bags (roughly 1000 to 1200 lb 454 to 544 kg) to get a salt system started will do the same; however, it will take much (b) longer to see the effects and for the pool to turn green. Salt needs to be added to the pool occasion- ally along with muriatic acid to maintain the correct pH level of 7.2 to 7.8. When muriatic acid is not added to a saltwater pool, the pH will rise, and the pool will become low in chlorine and high in the oxidizer ion, hypochlorite. This will not be nearly as visually obvious as the pool turning green when using with chlorine. The hypochlorite is a very aggressive chemical and will begin to eat away at everything it can—the pool plaster, metal railings, heater internals, and just about anything around the pool that is susceptible to corrosion—while the low chlorine level will keep the pool from turning green. Based on personal experience, when a residen- tial pool is well-maintained, a saltwater system makes for very nice and soft water. The salt cannot typically be tasted because the level of salt in a residential pool is under 4000 ppm, which is the typical human taste level of salt. In comparison, Fig. 3: Close-up views of a residential salt cell: ocean water is around 35,000 ppm. (a) information it provides and the adjustments The commercial saltwater pool is difficult to that can be made; and (b) close-up of the flow design, sell, and then to maintain correctly to sensor which shuts the cell off when there prevent premature deterioration due to the salt. is insufficient flow. Also shows the fins that There are two different types of commercial salt- provide the charges that separate the ions as water pools. One system has a separate tank in the salt water passes through Shotcrete • Summer 2014 29


2014SumShotcreteEMag
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