Pool Chemicals
During pool season a cornucopia of additives keeps pool water sparkling and clean.
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Maybe your mother told you, “Don’t drink the water,” but most swimmers probably give little thought to how much stuff is added to swimming pools to keep the water “balanced,” as the pool lingo goes. The water’s chemical balance dictates a pool’s physical condition, as well as swimmer comfort and safety.
If the water is too harsh, it can corrode equipment, dissolve concrete, or deposit mineral-based scale on pool tiles. Dissolved metals can cause staining; it’s too much copper, not chlorine, that causes green hair. But without chemical sanitizers, green, yellow, and black algae can completely take over, making pool walls slimy and slippery.
A dizzying array of specialized pool products exists, but among pool chemicals, the protagonist is definitely chlorine, the traditional water sanitizer. A residual level of just a few parts per million of chlorine must be maintained to keep microorganisms at bay.
For many, chlorine comes to mind because of many pools’ “chlorine smell.” This odor is actually from chloramines, produced by hypochlorous acid reacting with nitrogen-containing contaminants introduced by swimmers. A pool with enough added chlorine to oxidize the chloramines would have no smell, explains a technical expert at Arch Chemicals. The chlorine smell is a tip-off to pool owners that they need to “shock,” or increase the chlorine concentration.
Besides the chemicals to do basic sanitation, pH tuning, and calcium adjustment, there are also biocides, oxidizers, scale inhibitors, clarifiers, flocculants, metal removers, surface cleaners, and defoamers, to name a few. For the spa or hot tub market, there are also softeners and fragrances.
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Excerpted with permission, Chemical & Engineering News
Copyright © 2007 American Chemical Society