Swimming Pool Chemical Technology Automation

In science, oxidizers accept electrons. Reducers lose electrons. An increase in oxidation will result in a decrease in reduction, and vice versa. Chlorine is an oxidizer and provides a positive ORP. The ORP electrode uses an inert metal (platinum or gold) that will give up electrons to an oxidant and accept electrons from a reductant. The variables which affect ORP readings are temperature, total dissolved solids, cyanuric acid levels and pH, but the greatest factor is pH. As the pH of the water goes up, the effectiveness of the chlorine goes down. This produces fewer millivolts, hence a lower ORP. Any oxidizer (chlorine, bromine, ozone, iodine, non-chlorine shock, chloramines or hydrogen peroxide) in the water will have an ORP. The recommended range of ORP level is 650 mV to 750 mV.

The Power Of Ozone

The best way to understand ozone is to go outside after a thunderstorm. Ozone produces that fresh, clean scent you notice. Ozone is a reactive, unstable gas found in nature. It is a powerful, naturally occurring oxidizer that has been used safely in swimming pools and spas.

Ozone occurs in nature in two ways–through UV radiation from the sun or electrical energy from lightning strikes. High-energy ultraviolet radiation strikes an oxygen molecule and causes it to split into two free oxygen atoms, then the free oxygen atoms collide with molecules of oxygen to form O3 or ozone molecules. The UV radiation ozone is used in most small-pool applications as well as portable spas. The other type of ozone is produced by the Corona discharge reaction. This reaction uses high electrical voltage to split the O2 in oxygen atoms that form O3. Ozone is a powerful oxidizer and eliminates the need for manual shocking in most cases.

The Move To UV Water Purifiers

With the increasing popularity of interactive water features, aquatic facility managers are faced with protecting users from challenging sanitation and bacteriological concerns. Several states are now incorporating ultraviolet (UV) water purification systems into their public codes. Ultraviolet treatment of pool water photo-oxidizes and destroys combined chlorine and other pollutants. This provides major improvements to the pool environment and water quality, yet with significantly lower levels of chlorine. The combination of chlorine, combined chlorine (chloramines) and ozone in an indoor facility can be very corrosive to equipment. UV purifiers replace ozone and control chloramine levels, eliminating the chlorine odors bathers may experience in some indoor environments.

Carbon Dioxide Lowers pH

The issue of chemical handling is a major cost factor in most aquatic facilities, and threatens not only the public, but the aquatic staff, which historically is responsible for handling the chemicals. Most aquatic facility managers have used either sodium hypochlorite or calcium hypochlorite as the sanitizer of choice. Because both raise the pH, sodium hypochlorite and calcium hypochlorte are used in combination with muriatic acid to lower the pH.

As more aquatic managers attempt to make their equipment room environmentally safe, the use of carbon dioxide in place of muriatic acid is becoming more prevalent. Carbon dioxide, like muriatic acid, lowers pH.

When dissolved in water, it produces carbonic acid, which lowers pH, but unlike muratic acid, it has the tendency to increase total alkalinity.

Handle With Care

As a caution, since carbon dioxide is heavier than air, colorless and odorless, the storage of CO2 should be in a forced ventilation room. It is recommended that the handling of CO2 cylinders should be done by trained staff, much like the handling of chlorine gas tanks in the past. Again, as with all chemical feeders we have discussed, the CO2 should be injected into the circulation line downstream (return line) of all filtration equipment, including the sanitizer injection.

Automated Chemical Controllers Help Reduce Risk

Reducing risk from recreational water illness is a compelling reason to also install a complete, automated control system. Some aquatic professionals may shy away due to initial costs of chemical sensors and control systems; however, if you want to encourage people to visit and use your facilities, you must continue to find ways to reduce the risk of disease outbreaks. Aquatic facilities with automatic controllers have proven to reduce the number of recreational water illnesses, and therefore worth the initial investment.

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