Legionnaires' disease is a severe lung infection caused by the bacterium Legionella pneumophila. It does not spread from person to person; instead, it is transmitted by inhaling contaminated water droplets and aerosols. Common sources include showerheads, hot and cold water systems, cooling towers, spas, whirlpools, and jacuzzis.

Legionnaires' Disease Risk in Turkey

Due to high tourism activity, large water installations, and extensive international travel, Legionnaires' disease is considered a significant public health concern in Turkey. Since 1996, the disease has been monitored within the “Legionnaires' Disease Control Program,” which mandates various preventive measures for high-risk facilities.

Risk Factors

People at increased risk of developing Legionnaires' disease include:

• Being over 50 years old
• Male gender
• Smoking
• Chronic lung disease
• Weakened immune system
• Alcohol dependence
• Underlying medical conditions such as diabetes, cancer, organ transplantation
• Exposure to old or poorly maintained water systems

Environments Where Legionella Thrives

• Hot water tanks and hot water distribution systems
• Cold water systems above 20°C (68°F)
• Cooling towers and evaporative cooling units
• SPA pools, thermal baths, whirlpools
• Decorative fountains and artificial ponds
• Respiratory therapy devices in hospitals
• Dental unit waterlines
• Eye wash stations and fire sprinkler systems

Modes of Transmission

Legionella spreads primarily through two mechanisms:

1. Inhalation of Aerosols

• Fine droplets released from showerheads
• Aerosols dispersed from cooling towers
• Steam generated by spas, whirlpools, and jacuzzis
• Humidifiers and misting devices

2. Aspiration

Accidental inhalation or aspiration of contaminated water into the lungs can also lead to infection.

Common Locations Where Legionella Is Present

• Hotels
• Hospitals
• Shopping malls and restaurants
• Sports and fitness centers
• Campsites
• Factories and industrial facilities
• SPA and thermal centers
• Ships and ventilation systems

Preventive Measures for Facilities

• Assign trained personnel responsible for Legionella risk management
• Clean hot water tanks every 3 months and cold water tanks every 6 months
• Maintain hot water tank temperatures at a minimum of 60°C (140°F)
• Ensure that tap water reaches 50–60°C (122–140°F) within 1 minute
• Eliminate unused pipe sections and dead legs
• Flush taps and showers in unoccupied rooms for at least 3–5 minutes daily
• Regularly descale and disinfect showerheads
• Perform mechanical cleaning of cooling towers at least twice a year
• Disinfect heating and plumbing systems annually

Procedures Before Reopening a Facility

• Increase hot water system temperature to 70°C (158°F) and maintain it for 24 hours
• Flush all taps and showers for 5–10 minutes before use
• Apply system-wide hyperchlorination (minimum 3 ppm)
• Remove, clean, and disinfect showerheads
• Fully drain and disinfect cooling towers

Water Sampling and Monitoring

To effectively control Legionella risk, facilities must conduct monthly water sampling and ensure continuous implementation of appropriate biocide applications.

Conclusion

Legionnaires' disease represents a serious health risk in large facilities such as hotels, hospitals, and SPA centers. Regular system maintenance, temperature monitoring, proper disinfection, and routine water analysis are essential for safeguarding public health and complying with regulatory requirements.

To maintain a clean, safe and efficient swimming pool system, filtration, backwashing, rinsing and vacuuming procedures must be performed correctly. These operation guidelines ensure consistent water quality, protect public health and extend the lifespan of pool equipment.

Filtration (FILTER)

Filtration is the standard operating mode of the pool. The balance tank valve is fully opened, the main drain valve is opened between 20–50%, and the vacuum valve remains closed. The multiport valve is set to “FILTER” and the pump is started. The pressure gauge should read between 0.5 and 1 bar.

If the pressure rises by approximately 50% from the initial value, the filter is considered dirty and requires backwashing followed by rinsing.

Backwash (BACKWASH)

Over time, dirt and debris clog the pores between the filter sand grains, causing the internal pressure of the filter to rise. When the gauge reaches the yellow or red zone, backwashing is required. The multiport valve is set to “BACKWASH,” the pump is started and dirty water is discharged directly to waste.

During this operation, suction can be taken from the main drain or the balance tank.

Rinse (RINSE)

After backwashing, rinsing is necessary to prevent debris on the filter surface from returning into the pool. The valve is switched to “RINSE,” the pump is started and the operation continues until clean water appears through the sight glass.

Waste (WASTE)

When a large amount of sediment is present on the pool floor or when water must be discharged without contaminating the filter, the “WASTE” mode is used. In this mode, water bypasses the filter and flows directly to the drainage system. Pools without a natural drainage valve can also be emptied entirely using this method.

Recirculate (RECIRCULATE)

In this mode, pool water bypasses the filter and is returned directly to the pool. It is used when rapid water circulation is required without filtration.

Closed (CLOSED)

The “CLOSED” setting is used when maintenance is required on the pipeline between the pump and the filter or when the pool is taken out of service for the winter season.

Important: The pump must never be running while changing the multiport valve position.

Overflow Pool Operating Instructions

Overflow pools operate using balance tanks and channel systems to maintain proper circulation.

• Never open or close any valves while the pump is running.
• Never turn on underwater lights when the pool is empty.
• Never mix chlorine and acid in the same container.

A - Filtration Procedure

This is the daily operating mode of the pool and ensures continuous water cleanliness.

1. Stop the pump.
2. Set the multiport valve to “FILTER.”
3. Half open the main drain valve.
4. Fully open the balance tank valve.
5. Ensure the vacuum valve is closed.
6. Fully open the return (discharge) valve.
7. Close the waste valve.
8. Start the pump and check the pressure gauge.

B - Vacuuming Procedure

This procedure is used to clean dirt and debris accumulated on the pool floor.

1. Stop the pump.
2. Set the valve to “FILTER.”
3. Close the main drain valve.
4. Half open the balance tank valve.
5. Fully open the vacuum valve.
6. Fully open the return valve.
7. Open the waste valve.
8. Open the vacuum lid in the pool and connect the vacuum hose.
9. Start the pump and perform the vacuuming operation.

After vacuuming, clean the pump’s pre-filter basket thoroughly and reassemble it.

Backwash and rinse must be performed afterwards.

C - Backwash Operation

Backwashing is performed when the filter becomes dirty. It must also be carried out after every vacuuming task.

1. Stop the pump.
2. Set the multiport valve to “BACKWASH.”
3. Close the main drain valve.
4. Fully open the balance tank valve.
5. Ensure the vacuum valve is closed.
6. Close the return valve.
7. Open the waste valve.
8. Start the pump and continue until the sight glass shows clear water.

D - Rinse Operation

Rinsing must always be done after backwashing to reset the filter bed and prevent dirty water from returning to the pool.

1. Stop the pump.
2. Set the valve to “RINSE.”
3. Close the main drain valve.
4. Fully open the balance tank valve.
5. Ensure the vacuum valve is closed.
6. Close the return valve.
7. Open the waste valve.
8. Start the pump and continue until the water runs clear.

After rinsing, return the system to filtration mode.

Skimmer Pool Operating Instructions

• Do not operate valves while the pump is running.
• Do not turn on pool lights when the pool is empty.
• Never mix chlorine and acid together.

Swimming pools require balanced water chemistry, proper filtration and consistent maintenance. When these processes are disrupted, several swimming pool problems can occur, affecting water clarity, hygiene and equipment performance. This comprehensive guide explains the most common pool issues and provides professional, practical solutions for both residential and commercial pool operators.

1. Cloudy Pool Water

Cloudy water is one of the most common swimming pool problems. It indicates poor water quality and usually results from filtration issues or chemical imbalance.

Common Causes of Cloudy Water

• Dirty or clogged filter
• Low chlorine levels
• Unbalanced pH and alkalinity
• Insufficient circulation time
• Contaminants from swimmers such as oils and cosmetics

Solutions for Cloudy Water

• Perform a backwash to clean the filter
• Apply chlorine shock treatment
• Adjust pH to the ideal range of 7.2–7.6
• Increase daily pump running time
• Use a flocculant if necessary

2. Algae Growth

Green, yellow or black spots on pool walls are clear signs of algae growth. Algae not only makes the pool unattractive but can also create safety and hygiene risks.

Causes of Algae Growth

• Low chlorine levels
• Poor water circulation
• Insufficient brushing of pool surfaces
• Warm and sunny weather conditions

Solutions for Algae Problems

• Apply a strong chlorine shock treatment
• Brush pool walls and floor thoroughly
• Use a quality algaecide
• Increase filtration time

3. Unpleasant Pool Odors

Strong or unpleasant odors indicate poor water quality. Contrary to popular belief, this smell is not caused by too much chlorine but by chloramines created when chlorine reacts with organic waste.

Causes of Pool Odors

• High chloramine levels
• Low free chlorine
• Improper pH balance
• Accumulation of oils, sweat and cosmetics

Solutions for Pool Odor

• Perform chlorine shock to eliminate chloramines
• Adjust pH to the recommended range
• Improve filtration and circulation
• Encourage showering before entering the pool

4. pH and Chemical Imbalance

Incorrect water chemistry is one of the leading causes of swimming pool problems. High or low pH levels can damage equipment, irritate skin and eyes and reduce chlorine effectiveness.

Causes of Chemical Imbalance

• Incorrect chemical dosing
• Heavy pool usage
• Rainwater contamination
• Inaccurate water testing

Solutions to Restore Chemical Balance

• Adjust pH to 7.2–7.6
• Correct alkalinity levels
• Test water daily or weekly
• Use reliable chemical balancing products

5. Filtration System Problems

The filtration system is the heart of your pool. When it malfunctions, water can quickly become dirty, cloudy or unsafe.

Common Filtration Issues

• Dirty or saturated sand filter
• Undersized or weak pump
• Clogged pump basket
• Faulty multiport valve

Solutions for Filtration Problems

• Perform regular backwash
• Replace filter sand every 2–3 years
• Clean pump baskets frequently
• Inspect valves and pipes for leaks or blockages

6. Low or High Chlorine Levels

Chlorine levels directly affect water hygiene. The ideal range for free chlorine is 1–3 ppm.

Chlorine Problem Solutions

• Use shock chlorine if levels are too low
• If levels are too high, keep the pool closed temporarily
• Adjust pH to ensure chlorine efficiency
• Use stabilizer (CYA) in outdoor pools

Conclusion: Swimming Pool Problems Can Be Prevented with Proper Maintenance

Most swimming pool problems can be completely avoided with regular maintenance, balanced water chemistry and efficient filtration. Whether you manage a commercial pool or a private backyard pool, following the solutions in this guide will help maintain clean, safe and crystal-clear water all season long.