Clearing The Air

Ozone is a strong oxidizer of chloramines (chlorine disinfection by-products), which are formed when chlorine reacts with organic matter. Chloramines cause foul odors, irritation of the skin, eyes, and ears, and damage to indoor air-handling systems.

Also, new research is pointing to disinfection by-products (DPBs) as a cause of asthma in those who frequent aquatic facilities, especially those indoors. Installing an ozone-generator system will help to alleviate this concern because the DPBs are oxidized before they can affect bathers.

Ozone sanitizing improves water quality and bather comfort, while providing a safer, more pleasurable swimming experience.


A commonly voiced objection to installing Ozone technology is the upfront cost. As in any secondary sanitation method, the payback is based on savings to the end user.

Ozone destroys biofilm, which linger in filtration systems. By reducing the biofilm in the sand system, there is less cleaning and changing out of filtration media. Chloramines gas off, which can harm HVAC systems. By implementing Ozone technology, the structural corrosion of equipment is reduced.

The major chemical cost in an aquatic environment is chlorine treatment. The oxidation properties of Ozone can eliminate chlorine consumption by 50 percent. The operator no longer needs to “shock” the pool to oxidize–this is done continuously through the Ozone generator.

ORP Monitors

As state and local codes amend regulations to meet the sanitizer demand, many are now requiring Oxidation Reduction Potential (ORP) devices to measure the activity of the chlorine.

ORP relates to the oxidizing/reducing capability of the water by measuring the electron activity. The ORP probes only measure the ratio of oxidation. The electron activity is measured in millivolts (mV) with a recommended range of 650 mV to 750mV. ORP is only an indirect method to approximate the disinfectant level. Also, ORP measurements are influenced by the fluctuations in pH readings.

Although ORP does not specifically indicate the chlorine concentration in ppm, it does indicate the effectiveness of the chlorine as an oxidizer. An ORP reading will vary as pH fluctuates. As the pH increases, the millivolt reading on an ORP meter will decrease, indicating that the sanitizer is not as effective. Bringing the pH down or adding more sanitizer will raise the millivolt reading.

It is important that the operator calibrate the probes as part of the routine maintenance schedule because residue will build up on the probes and provide false readings. These are some of the reasons that manual testing with a DPD test kit is also required to ensure bather protection.


In order to effectively and efficiently monitor chemical-feed systems, it is vital that controllers be utilized to continuously feed the appropriate dosages. Controllers actually have the capability to read current disinfectant (either in ppm or ORP), pH levels, and alkalinity, sending an appropriate message to the chemical-induction feeders.

The message sent tells the feeders to add the correct chemical in order to achieve water balance, as well as chlorine demand.

The probes, which read chemical parameters, should be cleaned and maintained to remove residue buildup, which may interfere with readings. Operators should consult manufacturers’ instructions on how to properly clean the probes to assure that correct readings are being made.

It’s About Education

Keeping visitors comfortable and returning is the key to operating a successful aquatic facility. Critical to the health and safety of all is staying current with the changes in disinfection equipment, monitoring devices, and code requirements.

It takes time and research to understand the differences between the various systems available; attending as many education venues on these systems is recommended. This technology is the future, and the future is now.

Embracing as much knowledge as possible about these systems will create a safe and healthy environment for swimmers, as well as reducing risk and liability to the facility.

Connie Sue Centrella is a professor and Program Director for the online Aquatic Engineering Program at Keiser University eCampus. She is a five-time recipient of the Evelyn C. Keiser Teaching Excellence Award “Instructor of Distinction.” Centrella is an industry veteran with over 40 years experience in the pool and spa industry. She is a former pool builder with extensive knowledge in pool construction and equipment installation as well as manufacturing.




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