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THE SILVER INSTITUTE LETTER

VOLUME III, Number 5, May 1975

SILVER CARBON FILTER PURIFIES SWIMMING POOL

An activated carbon filter containing silver is responsible for "the cleanest swimming pool in the county," says a Maryland public health inspector. Swan dives may turn into bellyflops but for children and adults using the pool over the past 10 years there has been no case of ear infection, seriously irritated eyes or in-flamed membranes. The system purifies, removes odors and chemical taste in the water.

The silver filtering system has cut in half the cost of supplies and reduced the man-hours of maintenance work. The process also has eliminated the risks of flash fires, chemical buries or explosions that may accompany the use of some purifying agents. This pool is the North Severna Park Community Association installation near Annapolis, Md. The purification system was designed years ago by Dr. Charles E. Renn, then professor of sanitary engineering at Johns Hopkins University and two aides, William Chesney and M. Singh Dhillon. Mr. Dhillon now is Director of Environmental Health, Anne Arundel County 'Health Department; as such, he periodically checks to make sure that the pool meets public health requirements. He says: "The circulation and purification systems are so simple, they're fool-proof I can't understand why the system is not used more generally."

Because some other purifying chemicals are "pretty dangerous," he adds, the county health department gives special training courses for pool operators using them. The silver filter requires no special training. Members of the community association volunteer their time and experience to operate the association's facilities and Roy Yoerger is in charge of the swimming pool. He and Joseph D. Sebes, president, are strong advocates of silver and carbon for water purification. They use a Hyla filter, an early model of the filter tank now manufactured by Ionics, Inc., of Bridgeville, Pa. "The community wouldn't remotely consider going back to harsh chemical purification," he says. The 81,000 gallons in his main 30'x50' pool, plus 3,100 gallons from the baby pool, circulate constantly at the rate of 150 gallons per minute out of the pools, through three 500-gallon sand filters to remove solids, then part of the water goes through tile silver-carbon filter which is on a detour line flowing at 7.5 gallons per minute. Tile detour line rejoins the main line which returns to the pools. Every 9 hours the total volume of water in the pools is re-treated and because circulation is continual, there never is a chance for bacteria to build up. The filter itself is 3 cu. ft. of activated carbon of verv high surface area, coated with pure metallic silver. The silver is deposited in finely divided sieve form so that solubility is limited to meter trace quantities. Contaminated water contacting silver will dissolve or release minute amounts of silver: 25 to 40 parts per billion (easily within the U.S. Public Health Service definition of potable water) which kills the bacteria.

For more information on health hazards such as chlorine and other drinking water contaminants please read through our "Health Topics" pages or review many of the information sites listed on our research page.

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