As salt pools gain popularity in many areas of the country, we think it is a good time to provide some handy facts and tips for salt pool owners and operators.
Salt pools generate chlorine for sanitation.
Salt pools obtain their chlorine residual by means of “chlorine generators” (electrolysis devices) that use electricity to produce chlorine from salt (sodium chloride) dissolved in the pool water. Chlorine in the water—whether added this way or by EPA-registered pool sanitizers–destroys many common waterborne pathogens within seconds, helping to keep swimming healthy. Without pool water sanitizers, swimmers are vulnerable to contracting diarrhea, swimmer’s ear and skin infections.
Tip: Salt pool owners can use pool test strips to ensure appropriate pool chemistry, including pH and chlorine level. This summer, swimmers and pool owners can order a free pool test kit at www.healthypools.org/freeteststrips/.
Tip: Salt chlorine generators are rated for the pool size and the average “bather load” or number of swimmers. Owners and operators should engage the “boost cycle1” (which increases the chlorine level) to oxidize impurities on a regular basis according to manufacturer’s instructions or at least once per week. The boost cycle should also be used when anticipating an influx of additional swimmers. If the increased number of swimmers is very large (your child’s entire class from school or their sports team, or a pool party for example) the capacity of the generator may be overwhelmed—even in the boost cycle mode—requiring supplementing with a chlorine sanitizer product.
Tip: Saline water in salt pools may be diluted in the event of heavy rains, requiring additional salt to the pool system. Storms can also add environmental debris, requiring additional chlorination.
Tip: Adding chemicals to salt water pools could increase the level of sodium chloride salt in the pool because salt is sometimes contained in those products. It could be necessary, therefore, to reduce the amount of pool grade salt added to the pool system to account for salt’s presence in other pool chemicals.
Salt pools require maintenance.
Just as there is “no such thing as a free lunch,” there is also no such thing as a maintenance-free swimming pool. Calcium builds up on metal plates in the chlorine generator and plates have a limited expected lifetime.
Tip: Clean plates at appropriate intervals to remove calcium build-up per manufacturer’s directions. Also replace plates at the manufacturer’s recommended frequency to ensure the unit produces adequate chlorine.
Tip: Saline water is corrosive, especially to metals, maintenance and replacement of metal parts may be required in the pool environment. In dry climates where evaporation rates are relatively high, corrosive salt deposits may form on fixtures around the pool. Improperly sealed mortar in stonework may also be damaged.
Tip: Always ensure that the filtering system for the pool is properly maintained and functions well, especially when bather load is heavier than normal (lots of swimmers in the pool). Properly maintained filters and sanitizer levels are critical in both salt water and fresh water pools.
Impure salts added to salt pools can lead to unwanted substances and/or byproducts in pool water.
Only high-purity salts should be used in salt water pools to avoid harmful or unwanted substances in the pool water. For example, utilizing food-grade iodized salt could produce iodine levels in the pool of potential health concern. Salt containing high levels of calcium will coat the plates in the chlorine generator reducing the production of chlorine.
Tip: Add only “pool grade” salt to salt pools.
Fred Reiff, P.E., is a retired official from both the U.S. Public Health Service and the Pan American Health Organization, and lives in the Reno, Nevada area.
1The boost cycle refers to increased levels of disinfectant added quickly to pools (when swimmers are absent from the pool) to oxidize contaminants.