Silver is used as a powerful bactericide in many products, and copper is used as a common algaecide. As water contacts these minerals, positively charged ions are released; these destroy negatively charged contaminants. And that makes these particular minerals well-suited for use as supplemental sanitizers in residential swimming pools and portable spas.
Ions at work
Silver and copper are most effective in water in their ionic form. That means the molecules are independent from other compounds and carry a positive charge. These charged ions are attracted to negatively charged organics such as bacteria and algae. Once attached, these ionic elements destroy the organics by penetrating their cell walls.
Because the ions are unaffected by sunlight or heat, they can remain active in water for long periods. They are only removed by reacting with the organics or from splash-out. There must be a constant flow of these charged ions introduced to the water in order for this process to be effective.
Active and passive ionization
There are two types of devices manufactured today that accomplish this process — one using an active method and the other using a passive method.
Active-method devices create ionic silver and copper by applying a low-level direct current to electrodes that are plumbed into the filtration system. The electrodes, which are made from combinations of silver, copper and sometimes zinc, quickly release their ions into the water as they erode from electrolysis. The electrodes must be replaced periodically, and the water must be tested regularly to ensure the silver and copper levels do not rise to a point where staining could occur.
Sequestering agents are recommended with this method to prevent any possibility of staining. These devices were common in the 1980s and ‘90s, but they never reached mainstream status as sanitizers. Most pool professionals feel they were oversold as a total replacement to chlorine, or were installed and used improperly. Recent technology seems to take into account the lessons learned from the past, but ionizers are not what most people think of when mineral sanitizers are discussed.
Passive-method devices are usually what come to mind when discussing mineral sanitizers. They do not use any electricity, instead utilizing a flow-through cartridge containing a substrate that is coated with silver or impregnated with a combination of silver and copper. The substrate is made of small pebble-sized pieces that are retained in the plastic cartridge. The cartridge is then installed in a vessel that is plumbed into the pool’s filtration system. As the water passes over the substrate, silver ions or a combination of silver and copper ions are slowly released.
Sequestering agents are not necessary, since the ions are released so slowly. The cartridge contents will remain active for up to 6 months in pools and 4 months in portable spas. Passive devices are also a perfect complement to salt-water chlorinators. They do not interfere with chlorine generation, and many users find that they can turn the chlorine production rate down, making the electrolytic cell last longer. Passive devices are a preferred method of using copper and silver vs. adding them via a powder or liquid form, because those products usually are mixed with chemicals.
The U.S. Environmental Protection Agency plays an important role in the regulation of mineral sanitizers. While the copper and silver elements are considered safe, when an efficacy claim is made regarding algae or bacteria control, the EPA regulates its use. Therefore, make sure the product you use has an EPA registration number, lists the active ingredients, and shows all the cautions that the EPA requires. Though the EPA regulates and verifies the claims of mineral sanitizers, they do not regulate the product’s potential to stain or cause other problems. Look for products that are guaranteed to work and guaranteed not to stain the pool.
Benefits of mineral sanitizers
Neither the active nor passive methods eliminate the need for chlorine in a swimming pool, because minerals lack the ability to oxidize dead contaminants. Fortunately, the two biggest benefits of using minerals are a reduction in the amount of chlorine needed to maintain a residual, and the ability to maintain a lower residual. With a mineral sanitizer, you will notice at least some of the following:
No more algae
Fewer complaints about skin and eye irritations
Fewer shock treatments required
Fewer pH adjustments needed
The TDS reading does not increase as quickly
The best testimonials for mineral sanitizers come from the pool professionals who use them. They report many benefits, such as getting rid of problem algae spots, lowering chlorine use, more consistent chlorine readings, and pools that stay sparkling clear with less work.