Operation and Maintenance Flashcards

Assuming that your local health department requires you to raise the free chlorine to 5 ppm, how much sodium hypochlorite would be needed to raise the free chlorine in the pool to that level?

Answer: 3.5 gallons

To calculate the amount of sodium hypochlorite needed, one must know the pool's volume and the concentration of the chlorine product. Assuming a typical pool volume (e.g., around 40,000 gallons) and a common liquid chlorine concentration (e.g., 10-12.5%), approximately 3.5 gallons of sodium hypochlorite would be required to increase the free chlorine level by 5 ppm. This calculation ensures the correct dosage is applied to achieve the desired sanitation level.

You are the CPO for an indoor health club pool. The facility manager informs you that he is receiving complaints about a strong chlorine odor in the pool area, and several members have complained of eye irritation. The most likely cause of these complaints is:

Answer: high levels of chloramines in the pool

A strong chlorine odor and eye irritation in a pool are classic indicators of high levels of chloramines, not too much free chlorine. Chloramines are formed when free chlorine reacts with nitrogen-containing compounds from swimmer waste (sweat, urine, etc.). These compounds are ineffective disinfectants and are responsible for the unpleasant 'chlorine smell' and irritant effects, signaling poor water quality and the need for breakpoint chlorination or shocking.

To adjust the tested Total Alkalinity in the pool to an acceptable level, which chemical would be most appropriate?

Answer: Sodium Bicarbonate

Total Alkalinity (TA) is a measure of the water's ability to resist changes in pH. If the TA is too low, the pH will fluctuate wildly, leading to water balance issues. Sodium Bicarbonate (baking soda) is the most appropriate chemical to increase Total Alkalinity in pool water without significantly impacting other parameters like pH or calcium hardness, effectively stabilizing the water's pH.

To adjust the tested pH in the pool to an acceptable level, which chemical would be most appropriate?

Answer: Sodium Carbonate

Sodium Carbonate, commonly known as soda ash, is an alkaline chemical used to increase the pH level in pool water. If the tested pH is too low, adding sodium carbonate will raise it to the acceptable range (typically 7.4-7.6), which is crucial for bather comfort, sanitizer effectiveness, and preventing corrosion of pool equipment.

You are the CPO for a large municipal swimming pool. This pool has a volume of 560,000 gallons of water and has an average daily bather load of 1300 people. The pool is operated using high-rate pressure sand filters. How often should you backwash the filters?

Answer: When the influent and effluent gauges are 10 to 20 psi apart

Filter backwashing is primarily triggered by a pressure differential, not a fixed time interval. As debris accumulates in the filter media, it restricts water flow, causing the pressure on the influent (incoming) side to rise and the effluent (outgoing) side to drop. A significant pressure difference, typically 10 to 20 psi above the clean filter pressure, indicates the filter is dirty and needs backwashing to restore proper flow and filtration efficiency.

Safety and rescue equipment should always be:

Answer: kept easily accessible around the pool

In an emergency, immediate access to safety and rescue equipment is critical for a rapid and effective response. Keeping items like life rings, shepherd's hooks, and first aid kits easily accessible around the pool ensures that rescuers can quickly retrieve and deploy them, potentially saving lives or preventing serious injuries. Storing them in locked rooms or offices would cause dangerous delays.

Which type of filter system will remove the smallest micron particles?

Answer: Diatomaceous earth

Diatomaceous earth (DE) filters are renowned for their superior filtration capabilities, able to remove particles as small as 1-5 microns. This is significantly finer than rapid rate sand filters (20-100 microns) or cartridge filters (10-20 microns). The microscopic, porous structure of DE powder acts as a highly effective sieving agent, resulting in the clearest possible pool water.

If the pump fails to prime, which of the following does not have to be checked?

Answer: Filter system pressure is too high

A pump failing to prime indicates an issue on the suction side, preventing water from reaching the pump impeller. High filter system pressure, however, is a symptom of a dirty filter or a blockage *after* the pump (on the discharge side), which would not prevent the pump from initially drawing water. Leaks on the suction side, a loose hair and lint cover, or a clogged skimmer basket all directly impede the pump's ability to pull water and prime.

Oxidation Reduction Potential testing (ORP) is measured in?

Answer: mV

Oxidation Reduction Potential (ORP) measures the oxidizing power of the sanitizers in the water, indicating their effectiveness in killing contaminants. This electrochemical measurement is expressed in millivolts (mV), reflecting the electrical potential difference in the water. Higher mV readings generally correlate with more effective sanitation and healthier pool conditions.

Channeling of filters occurs when:

Answer: the FMR is exceeded, and water cuts a channel through the media

Channeling occurs when water flows too quickly through a filter, often due to an excessive Filter Media Rate (FMR). Instead of being evenly distributed and filtered, the water carves preferential paths or 'channels' through the filter media. This bypasses the media, leading to ineffective filtration and allowing unfiltered water to return to the pool.