CPO key terms

The time in hours required to circulate a volume of water equal to the entire pool volume through the filtration system. It drives pump sizing and the number of daily turnovers needed for clarity and sanitation.

The volume of water moving through the circulation system per unit of time, usually gallons per minute. It must be matched to the filter, heater, and chemical feeder ratings.

The mechanical removal of suspended particles from pool water by passing it through a porous medium. It complements but never replaces chemical disinfection and circulation.

The granular or fabric material inside a filter that traps debris, such as sand, diatomaceous earth, or cartridge fabric. Each type has its own flow limits and cleaning method.

Reversing water flow through a filter to flush trapped debris to waste. It is performed when pressure differential rises or on a set schedule, and the filter must be rinsed before returning to service.

The difference between filter inlet and outlet pressure, read on gauges. A rising differential signals clogged media and the need to backwash or clean the filter.

The portion of chlorine in water that remains active and available to kill pathogens and oxidize contaminants. It is the value tested to confirm disinfection, distinct from combined chlorine.

Chlorine that has reacted with nitrogenous waste such as ammonia or sweat to form chloramines. It is a weak disinfectant and causes eye and respiratory irritation, so it is measured separately.

Adding enough chlorine to oxidize all combined chlorine and leave a measurable free chlorine residual. It is used to clear chloramine buildup and requires the pool to be closed to bathers during treatment.

A stabilizer that slows chlorine loss from sunlight in outdoor pools. It also reduces chlorine's effective strength, so levels must be kept within a moderate range and monitored with testing.

A scale from 0 to 14 expressing how acidic or basic water is, with 7 neutral. It affects disinfectant efficiency, bather comfort, and scaling or corrosion of pool surfaces and equipment.

The water's capacity to resist changes in pH, measured mainly as bicarbonate. Proper alkalinity buffers pH swings; too high makes pH drift up and too low makes it unstable.

The concentration of dissolved calcium in pool water. Too low corrodes and leaches surfaces; too high causes scale, cloudy water, and deposits on heaters and tiles.

A calculated number combining pH, temperature, calcium hardness, alkalinity, and dissolved solids to predict whether water is scaling or corrosive. A near-zero value indicates balanced water.

A large, rapid dose of oxidizer added to destroy organic waste, chloramines, and contaminants. It is not the same as routine chlorination and usually requires keeping bathers out until levels fall.

A device that injects or dissolves sanitizer or pH-adjusting chemicals into the circulation line at a controlled rate. It must be sized and installed so it cannot backfeed into the pool or potable supply.

A device at the waterline that draws surface water and floating debris into the circulation system. It also provides the suction point for vacuuming and must be kept clear to maintain flow.

An outlet at the deepest part of a pool that draws water to the pump and drains the pool. It must be fitted with a compliant anti-entrapment cover to prevent suction entrapment.

A specially designed grate or cover for a pool outlet that limits suction force and prevents body or limb entrapment. It must be the correct size, securely fastened, and never replaced with a generic grate.

A hazardous condition in which a bather is held underwater or against an outlet by suction or by body, hair, or limb capture. Prevention relies on compliant covers, dual drains, and emergency shutoff.

A clearly marked switch that stops the circulation pump instantly in an emergency. Staff must know its location and how to use it to release a suction entrapment.

Any actual or potential link between potable water and a pool or chemical system that could allow backflow. Prevention uses air gaps, backflow preventers, and proper plumbing separation.

A device or arrangement such as an air gap or check valve that stops contaminated water from reversing into the drinking-water supply. It is required wherever pool or chemical lines connect to potable water.

Keeping pool chemicals in a cool, dry, ventilated area, separated by type and away from incompatible substances. Acids and chlorine products must never be stored together or share scoops.

Safety Data Sheet: a standardized document describing a chemical's hazards, handling, first aid, and spill response. It must be readily accessible to workers for every hazardous chemical on site.

Gear such as gloves, goggles, aprons, and respirators worn to shield the body from chemical splashes and fumes. It must be selected for the specific task and inspected before use.

A trained, certified person responsible for supervising bathers, enforcing rules, and performing rescues and first aid. Their primary duty is continuous surveillance of the assigned zone.

The specific area of water and deck a lifeguard is assigned to watch, with clear boundaries. Overlapping or unclear zones create blind spots where drowning can be missed.

A surveillance guideline: scan the entire assigned zone every 10 seconds and be able to reach any point in it within 20 seconds. It helps lifeguards maintain coverage and response readiness.

The act of removing a person in distress from the water safely, using reach, throw, or go techniques appropriate to the situation. It includes assessment, extrication, and follow-up care.

Techniques used to limit movement of a suspected head or neck injury during rescue and removal from the water. It aims to prevent further harm while allowing necessary airway care.

A written, rehearsed procedure assigning roles for rescues, first aid, EMS contact, and facility control during an incident. Staff must practice it regularly so response is automatic.

The maximum number of people permitted in a pool or facility at one time, based on water surface area and deck space. Exceeding it raises contamination and supervision risk.

How clearly the pool bottom and main drain are visible through the water. Poor clarity prevents drowning detection and signals filtration or chemistry failure, so the pool may need closing.

The procedure for closing, disinfecting, and reopening a pool after contamination, with contact time and chlorine levels set by the type of accident. Formed and diarrheal events require different responses.

Illness caused by pathogens or chemicals in pools and spas, often from swallowing contaminated water. Prevention depends on disinfection, hygiene rules, and proper incident response.

A device that detects a blockage in a suction outlet and automatically shuts off or vents the pump to break the suction. It is one layer of protection against entrapment.

A physical separation between a water supply outlet and the pool or vessel rim, preventing backflow by gravity. It is the most reliable form of backflow protection.