CERTIFIED POOL OPERATOR EXAM
PRACTICE QUESTIONS AND CORRECT
ANSWERS 2026/2027
whole range chlorine in a pool: ____ to _____ - ANSWER-1, 5
ideal range chlorine in a pool: ____ to _____ - ANSWER-2, 4
whole range chlorine in a spa: ____ to _____ - ANSWER-2, 10
ideal range chlorine in a spa: ____ to _____ - ANSWER-3, 5
4 types of solid chlorine - ANSWER-calcium hypochlorite, lithium hypochlorite, trichlor,
dichlor
liquid chlorine - ANSWER-sodium hypochlorite (NaOCl)
how active is gas chlorine - ANSWER-100%
the active killing form of chlorine in water - ANSWER-hypochlorous acid (HOCl)
HOCl = ______ - ANSWER-H+ (hydrogen ion) + OCl- (hypochlorite ion)
most common granular chlorine (pH range) - ANSWER-calcium hypochlorite (8.5 - 11,
used to super chlorinate water)
not common form of chlorine due to low active strength (pH) - ANSWER-lithium
hypochlorite (10.8)
tablet/stick chlorine usually used in erosion feeder (pH - what will it do?) - ANSWER-
trichlor (2.8 - 3.5, lower alkalinity and pH over time)
salt used as a disinfectant (pH) - ANSWER-dichlor (6.7 - common in vinyl lined pools)
most common type of chlorine used (pH) - ANSWER-sodium hypochlorite (NaOCl - 13)
______ needs special training to use and has a pH of ____ and will _____ when added
to water - ANSWER-gas chlorine, 0, lower pH
chlorine is most effective as a pH of _____ - ANSWER-7.5
active disinfectant in the water - ANSWER-free chlorine (FC)
, FC is determined by the ______ test and is maintained between ____ and ____ ppm -
ANSWER-DPD, 2, 4
equal to the amount of hypochlorous acid (HOCl) and the amt of hypochlorite ions (OCl-
) - ANSWER-free chlorine (fc)
the result of free chlorine reacting with organic compounds - ANSWER-combine
chlorine (CC)
common name and max for pools and spas for combine chlorine - ANSWER-
chloramines, 0.2, 0.5
CC = - ANSWER-TC - FC
what will a DPD measure - ANSWER-TC, FC
how much CC should a pool have ideally - ANSWER-zero
shocking the pool is also called - ANSWER-breakpoint chlorination
breakpoint chlorination is the conversion of ________ into ______ - ANSWER-combine
chlorine, nitrogen gas
breakpoint chlorination equation - ANSWER-BPC = 10 x CC [BPC = 10 x (TC - FC)]
whole cyanuric acid range: _____ to ______ppm - ANSWER-0, 100
ideal cyanuric acid range: _____ to ______ ppm - ANSWER-30, 50
acts as a protection for chlorine compounds from UV light - ANSWER-cyanuric acid
CyA will act as a stabilizer for _______ but does not
stabilize ________ - ANSWER-free chlorine, bromine
The only way to reduce CyA concentration is to _______ - ANSWER-dilute the water
and replace it
whole range of bromine: ____ to _____ - ANSWER-2, 10
ideal range of bromine: _____ to ______ - ANSWER-4, 6
second most common disinfectant in the pool - ANSWER-bromine
two types of bromine used - ANSWER-sodium bromide, solid bromide
Bromine in natural form is a ______ but is in _____ form when
PRACTICE QUESTIONS AND CORRECT
ANSWERS 2026/2027
whole range chlorine in a pool: ____ to _____ - ANSWER-1, 5
ideal range chlorine in a pool: ____ to _____ - ANSWER-2, 4
whole range chlorine in a spa: ____ to _____ - ANSWER-2, 10
ideal range chlorine in a spa: ____ to _____ - ANSWER-3, 5
4 types of solid chlorine - ANSWER-calcium hypochlorite, lithium hypochlorite, trichlor,
dichlor
liquid chlorine - ANSWER-sodium hypochlorite (NaOCl)
how active is gas chlorine - ANSWER-100%
the active killing form of chlorine in water - ANSWER-hypochlorous acid (HOCl)
HOCl = ______ - ANSWER-H+ (hydrogen ion) + OCl- (hypochlorite ion)
most common granular chlorine (pH range) - ANSWER-calcium hypochlorite (8.5 - 11,
used to super chlorinate water)
not common form of chlorine due to low active strength (pH) - ANSWER-lithium
hypochlorite (10.8)
tablet/stick chlorine usually used in erosion feeder (pH - what will it do?) - ANSWER-
trichlor (2.8 - 3.5, lower alkalinity and pH over time)
salt used as a disinfectant (pH) - ANSWER-dichlor (6.7 - common in vinyl lined pools)
most common type of chlorine used (pH) - ANSWER-sodium hypochlorite (NaOCl - 13)
______ needs special training to use and has a pH of ____ and will _____ when added
to water - ANSWER-gas chlorine, 0, lower pH
chlorine is most effective as a pH of _____ - ANSWER-7.5
active disinfectant in the water - ANSWER-free chlorine (FC)
, FC is determined by the ______ test and is maintained between ____ and ____ ppm -
ANSWER-DPD, 2, 4
equal to the amount of hypochlorous acid (HOCl) and the amt of hypochlorite ions (OCl-
) - ANSWER-free chlorine (fc)
the result of free chlorine reacting with organic compounds - ANSWER-combine
chlorine (CC)
common name and max for pools and spas for combine chlorine - ANSWER-
chloramines, 0.2, 0.5
CC = - ANSWER-TC - FC
what will a DPD measure - ANSWER-TC, FC
how much CC should a pool have ideally - ANSWER-zero
shocking the pool is also called - ANSWER-breakpoint chlorination
breakpoint chlorination is the conversion of ________ into ______ - ANSWER-combine
chlorine, nitrogen gas
breakpoint chlorination equation - ANSWER-BPC = 10 x CC [BPC = 10 x (TC - FC)]
whole cyanuric acid range: _____ to ______ppm - ANSWER-0, 100
ideal cyanuric acid range: _____ to ______ ppm - ANSWER-30, 50
acts as a protection for chlorine compounds from UV light - ANSWER-cyanuric acid
CyA will act as a stabilizer for _______ but does not
stabilize ________ - ANSWER-free chlorine, bromine
The only way to reduce CyA concentration is to _______ - ANSWER-dilute the water
and replace it
whole range of bromine: ____ to _____ - ANSWER-2, 10
ideal range of bromine: _____ to ______ - ANSWER-4, 6
second most common disinfectant in the pool - ANSWER-bromine
two types of bromine used - ANSWER-sodium bromide, solid bromide
Bromine in natural form is a ______ but is in _____ form when
