CRYSTAL AQUATICS POOL OPERATOR
EXAM QUESTIONS WITH COMPLETE
SOLUTIONS
Sodium hypochlorite - Answer-Liquid chlorine, strong oxidizer with high pH
Range 1.5 - 4 ppm or ORP 650 - 750 mV
Calcium hypochlorite - Answer-Solid chlorine, HTH, raises calcium concentration
Chlorine gas - Answer-Most effective, 100% FAC, dangerous
Electrolysis (salt based Chlorine generation) - Answer-NaCl added to pool water, runs
through salt cell. Electric charge applied to plates, breaks Na off to form hypochlorous
acid
Combined chlorine - Answer-Abbreviated CC's, a.k.a. chloramines. Free chlorine acts
with contaminants to form these.
Total chlorine - free chlorine = combined chlorine
TC - FC = CC
If CC is above 0.2 ppm, super chlorinate pool
Super chlorination - Answer-Point at which all contaminants are oxidized
FC level must be raised to at least 10x CC level. If CC is 0.3 ppm, then 10x0.3 = 3
hyperchlorination - Answer-Hyperchlorination disinfects water and kills bacteria and
parasites. Raise Cl for a period of time, based on pathogen inactivation value.
Breakpoint Cl level - FC level = ppm change needed to hyperchlorinate
Cyanuric acid (CYA) - Answer-Water conditioner that stabilizes chlorine after exposure
to UV radiation
Maintain at 30 - 50 ppm
Not effective with bromine
More CYA = longer it takes to kill bacteria
pH - Answer-quantification of hydrogen ion concentration in a solution
ideal 7.5, range 7.2-7.8
Liquid Cl causes a rise in pH
Gas Cl causes a drop in pH
If high, add muriatic acid
If high, water scales: clouds water, blocks filters, white film
If low, add sodium carbonate (soda ash)
, If low, water is corrosive: stains surfaces, corrodes whitecoat, dissolves metal
Alkalinity - Answer-Ideal 80-120 ppm
Total alkalinity is water's ability to resist pH changes
If high, add muriatic acid
If high, water scales: clouds water, blocks filters, white film
If high, pH drifts upward
If low, add sodium bicarbonate
If low, water is corrosive: stains surfaces, pits concrete, dissolves metal
If low, pH bounces and is difficult to maintain
Calcium hardness - Answer-Ideal level 200-400 ppm
Calcium hardness: measure of calcium concentration in water
High Ca and Mg concentration = hard
Low Ca and Mg concentration = soft
If high, dilute with soft water
If high, water is scaling: clouds water, plugs filters, creates white film
If low, add calcium chloride
If low, water is corrosive: pits concrete and etches plaster
Temperature - Answer-Ideal pool 78-82 Fahrenheit, spa 104 Fahrenheit
High temperatures in spas = more likely to scale
Low temperatures in winterized pools = more likely to corrode
High temperatures in pools makes Chlorine break down faster
Disinfectants work effectively in ideal temp range
Saturation index - Answer-SI is the calculation used to determine if water is balanced
If low (below -0.3) it's corrosive with concrete etching and metal corrosion
If high (above 0.3) there is cloudiness and scaling
Contact time - Answer-CT values: amount of time necessary for inactivating pathogens
in the water
CT inactivation level / Chlorine level = time required to inactivate
Total dissolved solids - Answer-TDS is the measure of all organic and inorganic
dissolved solids in pool water
Increase due to solids like minerals, salts, metals in pool
EXAM QUESTIONS WITH COMPLETE
SOLUTIONS
Sodium hypochlorite - Answer-Liquid chlorine, strong oxidizer with high pH
Range 1.5 - 4 ppm or ORP 650 - 750 mV
Calcium hypochlorite - Answer-Solid chlorine, HTH, raises calcium concentration
Chlorine gas - Answer-Most effective, 100% FAC, dangerous
Electrolysis (salt based Chlorine generation) - Answer-NaCl added to pool water, runs
through salt cell. Electric charge applied to plates, breaks Na off to form hypochlorous
acid
Combined chlorine - Answer-Abbreviated CC's, a.k.a. chloramines. Free chlorine acts
with contaminants to form these.
Total chlorine - free chlorine = combined chlorine
TC - FC = CC
If CC is above 0.2 ppm, super chlorinate pool
Super chlorination - Answer-Point at which all contaminants are oxidized
FC level must be raised to at least 10x CC level. If CC is 0.3 ppm, then 10x0.3 = 3
hyperchlorination - Answer-Hyperchlorination disinfects water and kills bacteria and
parasites. Raise Cl for a period of time, based on pathogen inactivation value.
Breakpoint Cl level - FC level = ppm change needed to hyperchlorinate
Cyanuric acid (CYA) - Answer-Water conditioner that stabilizes chlorine after exposure
to UV radiation
Maintain at 30 - 50 ppm
Not effective with bromine
More CYA = longer it takes to kill bacteria
pH - Answer-quantification of hydrogen ion concentration in a solution
ideal 7.5, range 7.2-7.8
Liquid Cl causes a rise in pH
Gas Cl causes a drop in pH
If high, add muriatic acid
If high, water scales: clouds water, blocks filters, white film
If low, add sodium carbonate (soda ash)
, If low, water is corrosive: stains surfaces, corrodes whitecoat, dissolves metal
Alkalinity - Answer-Ideal 80-120 ppm
Total alkalinity is water's ability to resist pH changes
If high, add muriatic acid
If high, water scales: clouds water, blocks filters, white film
If high, pH drifts upward
If low, add sodium bicarbonate
If low, water is corrosive: stains surfaces, pits concrete, dissolves metal
If low, pH bounces and is difficult to maintain
Calcium hardness - Answer-Ideal level 200-400 ppm
Calcium hardness: measure of calcium concentration in water
High Ca and Mg concentration = hard
Low Ca and Mg concentration = soft
If high, dilute with soft water
If high, water is scaling: clouds water, plugs filters, creates white film
If low, add calcium chloride
If low, water is corrosive: pits concrete and etches plaster
Temperature - Answer-Ideal pool 78-82 Fahrenheit, spa 104 Fahrenheit
High temperatures in spas = more likely to scale
Low temperatures in winterized pools = more likely to corrode
High temperatures in pools makes Chlorine break down faster
Disinfectants work effectively in ideal temp range
Saturation index - Answer-SI is the calculation used to determine if water is balanced
If low (below -0.3) it's corrosive with concrete etching and metal corrosion
If high (above 0.3) there is cloudiness and scaling
Contact time - Answer-CT values: amount of time necessary for inactivating pathogens
in the water
CT inactivation level / Chlorine level = time required to inactivate
Total dissolved solids - Answer-TDS is the measure of all organic and inorganic
dissolved solids in pool water
Increase due to solids like minerals, salts, metals in pool
