Arizona ROC C-6 Swimming Pool Service and Repair Examination

A pool technician is calculating the volume of a rectangular swimming pool measuring 30 feet in length and 15 feet in width. The shallow end depth is 3 feet and the deep end depth is 9 feet, sloping uniformly. What is the total water volume of the pool in gallons?

• A20,250 gallons
• B27,000 gallons
• C13,500 gallons
• D30,375 gallons

A standard commercial high-rate sand filter has a effective filter surface area of 3.14 square feet. If industry standards limit the maximum filtration flow rate to 15 GPM per square foot of filter area, what is the maximum allowable circulation pump flow rate through this filter?

• A31.4 GPM
• B47.1 GPM
• C62.8 GPM
• D78.5 GPM

When recharging a 60-square-foot Diatomaceous Earth (DE) filter after backwashing, what is the standard recommended amount of DE powder to slurry and pre-coat onto the filter elements?

• A3.0 lbs to 4.5 lbs
• B12.0 lbs to 15.0 lbs
• C6.0 lbs to 9.0 lbs
• D1.5 lbs to 2.0 lbs

A technician is performing deep maintenance on heavily fouled cartridge filter elements covered in both organic oils and mineral scale. What is the correct order of chemical cleaning solutions to prevent permanently embedding scale into the fabric matrix?

• ASoak in degreasing solution first, rinse thoroughly, then soak in dilute muriatic acid so…
• BSoak in dilute muriatic acid solution first, rinse thoroughly, then soak in degreaser
• CSoak simultaneously in a mixed solution of muriatic acid and trisodium phosphate (TSP)
• DPressure wash at 3,500 PSI using cold water with no chemical pre-soak

A pool pump system reads a suction vacuum of 10 inches of mercury (in Hg) on the suction gauge and a discharge pressure of 20 pounds per square inch (PSI) on the filter pressure gauge. What is the Total Dynamic Head (TDH) of the circulation system in feet of head?

• A30.0 feet
• B46.2 feet
• C22.6 feet
• D57.5 feet

According to the affinity laws for centrifugal pool pumps, if a variable-speed pump's operating speed (RPM) is reduced by 50%, to what percentage of its original power consumption does the electric motor power drop?

• A50.0%
• B12.5%
• C25.0%
• D6.25%

A commercial pool holds 48,000 gallons of water. Local health code requires a complete water turnover every 6 hours. What minimum flow rate in gallons per minute (GPM) must the circulation system maintain?

• A80 GPM
• B100 GPM
• C133.3 GPM
• D160 GPM

A pool circulation pump is emitting a loud noise resembling gravel or marbles rattling inside the pump housing, accompanied by high suction vacuum gauge readings. What condition is occurring and what is the primary cause?

• APump cavitation caused by severe suction-side restriction such as a clogged skimmer or cl…
• BMotor bearing failure caused by electrical over-voltage
• CDischarge over-pressurization caused by a dirty filter or closed return valve
• DAir binder lock caused by an air leak in the pump strainer lid O-ring

What is the standard recommended pressure differential indicator that alerts a pool service technician that a sand or DE filter requires backwashing?

• A1 to 3 PSI drop below clean operating pressure
• B25 to 30 PSI increase above clean operating pressure
• C15 to 20 PSI drop below clean operating pressure
• D8 to 10 PSI increase above clean operating pressure

What is the primary function of the floating weir door installed in a surface skimmer throat?

• ATo regulate pump suction flow and prevent pump cavitation
• BTo increase surface water velocity into the skimmer and prevent trapped floating debris f…
• CTo equalize water level between the skimmer bucket and main drain line
• DTo prevent large debris like leaves from entering the skimmer basket

Which multiport valve setting diverts pool water straight from the pump through the valve to return piping, completely bypassing the filter media matrix?

• AWASTE
• BRINSE
• CRECIRCULATE
• DCLOSED

A technician notices steady streams of air bubbles blowing out through pool return fittings and air accumulating at the top of the pump pot clear lid. What is the most likely root cause?

• AA suction-side air leak located before or at the pump inlet, such as a dried pump lid O-r…
• BA cracked DE filter grid inside the pressurized filter tank
• CExcessive water pressure on the filter discharge line
• DHigh total dissolved solids (TDS) causing spontaneous outgassing in return lines

According to ANSI/APSP standards for pool plumbing design, what are the maximum recommended water flow velocities for suction piping and discharge (return) piping, respectively?

• A4 feet per second suction / 6 feet per second discharge
• B6 feet per second suction / 8 feet per second discharge
• C8 feet per second suction / 10 feet per second discharge
• D10 feet per second suction / 12 feet per second discharge

A variable-speed pool pump is throttled down from 3,450 RPM to 1,725 RPM. How does this speed reduction impact the system dynamic head pressure produced by the pump?

• AHead pressure drops to 50% of its original value
• BHead pressure drops to 12.5% of its original value
• CHead pressure remains unchanged
• DHead pressure drops to 25% of its original value

What condition in a sand filter causes unfiltered water to pass directly through channels in the sand bed back into the pool without effective dirt removal?

• AFilter bed mud-balling
• BBackwashing at too low a flow rate
• CChanneling caused by calcified sand, excessive flow rates, or oil binding
• DFilter lateral cracking

Shortly after adding fresh DE slurry to a pool skimmer, the technician observes white DE powder blowing directly out of the pool return jets into the basin. What defect is indicated?

• ATorn DE fabric grid element, broken manifold, or missing standpipe O-ring
• BExceeded maximum pump flow rate capacity
• CDE powder grade was too fine (#20 silica)
• DMultiport valve gasket reversed in RINSE position

What is the critical safety function of a hydrostatic relief valve installed in the main drain sump of a concrete swimming pool?

• ATo release excess water pressure from the circulation pump discharge header
• BTo relieve high underground water pressure beneath the pool shell by admitting groundwate…
• CTo automatically shut off pump suction if a swimmer blocks the main drain cover
• DTo drain the pool automatically when water level rises above skimmer level

A pool pump motor runs smoothly at rated speed, but the filter pressure gauge reads near zero PSI, flow at return jets is extremely weak, and the pump strainer basket remains full of water. What issue is indicated?

• AClogged main filter media bed
• BSuction air leak at the pump lid O-ring
• CBlown filter tank seal gasket
• DClogged or jammed pump impeller vanes

Why must a corrosion-resistant check valve be installed in the return line between an inline chemical feeder (such as a Trichlor erosion feeder) and the pool heater?

• ATo prevent highly concentrated acid/chlorine water from siphoning backward into the heate…
• BTo prevent pool water from overflowing the chemical feeder tank during normal operation
• CTo boost water velocity through the chemical feeder chamber
• DTo trap air before it reaches the pool heater pressure switch

What is the water capacity in gallons of a circular swimming pool with a diameter of 24 feet and a uniform water depth of 4.5 feet?

• A11,450 gallons
• B19,085 gallons
• C15,268 gallons
• D20,358 gallons

What mathematical multipliers are used to convert suction vacuum gauge readings in inches of mercury (in Hg) and discharge pressure readings in pounds per square inch (PSI) to feet of head, respectively?

• AMultiply in Hg by 2.31 and multiply PSI by 1.13
• BMultiply in Hg by 1.13 and multiply PSI by 2.31
• CMultiply in Hg by 0.433 and multiply PSI by 1.47
• DMultiply in Hg by 12.0 and multiply PSI by 8.33

After backwashing a sand filter, why must the multiport valve be set to 'RINSE' for 15 to 30 seconds before returning to the normal 'FILTER' position?

• ATo sterilize the sand bed with concentrated chlorine
• BTo re-pack the sand bed and purge residual dirty backwash water to waste, preventing a cl…
• CTo increase filter tank operating pressure
• DTo flush debris from the pump impeller housing out to waste

To ensure accurate volumetric GPM measurement, an inline pitot-tube or paddlewheel flow meter should be installed in a straight run of pipe clear of fittings by at least what distances?

• A10 pipe diameters upstream and 5 pipe diameters downstream
• B2 pipe diameters upstream and 2 pipe diameters downstream
• C20 pipe diameters upstream and 10 pipe diameters downstream
• D5 pipe diameters upstream and 10 pipe diameters downstream

Under the Virginia Graeme Baker (VGB) Pool and Spa Safety Act (ANSI/APSP-16), what is the maximum allowable flow velocity across a field-fabricated main drain suction grate unless specifically tested and rated by the manufacturer?

• A3.0 feet per second
• B6.0 feet per second
• C1.5 feet per second
• D0.5 feet per second

A pool pump installed 3 feet above pool water level fails to prime after 5 minutes of running. Which of the following is the most likely cause?

• ADischarge check valve installed backward
• BAir leak at the pump pot lid O-ring or dry pump housing without initial priming water
• CFilter pressure gauge reading 5 PSI too high
• DReturn line eyeball fittings adjusted downward

A system requires a suction flow rate of 60 GPM. To maintain water velocity at or below the code maximum of 6.0 feet per second (fps), what minimum Schedule 40 PVC pipe size must be installed for the suction line?

• A1.25-inch pipe
• B1.5-inch pipe
• C2.5-inch pipe
• D2.0-inch pipe

When sizing a cartridge filter for a residential swimming pool designed for a maximum circulation flow rate of 100 GPM, what minimum filter surface area is required if the manufacturer design rating specifies a maximum flow rate of 0.375 GPM per square foot of filter element area?

• A267 sq ft
• B150 sq ft
• C375 sq ft
• D100 sq ft

A pool technician calculates a Langelier Saturation Index (LSI) value of -0.65 for a plaster swimming pool. What condition does this LSI value represent, and what is the expected effect on the pool?

• AWater is corrosive and will dissolve calcium carbonate, etching plaster surfaces and corr…
• BWater is perfectly balanced with zero scaling or etching potential
• CWater is scale-forming and will deposit calcium carbonate scale on plaster walls and insi…
• DWater has excessive cyanuric acid causing chlorine lock

A DPD test kit reveals a Total Chlorine reading of 3.5 ppm and a Free Available Chlorine reading of 2.8 ppm. What is the concentration of Combined Chlorine (chloramines), and does it require corrective action?

• A0.7 ppm Combined Chlorine; requires superchlorination because it exceeds the 0.2 ppm thre…
• B6.3 ppm Combined Chlorine; requires immediate draining
• C0.7 ppm Combined Chlorine; acceptable level requiring no treatment
• D1.25 ppm Combined Chlorine; requires adding cyanuric acid

To achieve breakpoint chlorination and eliminate combined chlorine (chloramines) from a swimming pool, how many times the measured combined chlorine concentration must free available chlorine be raised?

• A2 times the combined chlorine concentration
• B5 times the combined chlorine concentration
• C10 times the combined chlorine concentration
• D20 times the combined chlorine concentration

What is the primary chemical effect on pool water when 31.45% (20° Baume) muriatic acid (hydrochloric acid) is added to a swimming pool?

• ARaises pH and raises Total Alkalinity
• BLowers pH and lowers Total Alkalinity
• CLowers pH while raising Total Alkalinity
• DRaises Total Alkalinity without altering pH

A technician needs to raise the Total Alkalinity of a 20,000-gallon swimming pool by 20 ppm. If adding 1.5 pounds of sodium bicarbonate (baking soda) raises Total Alkalinity by 10 ppm per 10,000 gallons of water, how much sodium bicarbonate is required?

• A3.0 lbs
• B4.5 lbs
• C6.0 lbs
• D8.0 lbs

What is the recommended ideal range for Calcium Hardness in a plaster swimming pool to maintain water balance and prevent plaster degradation?

• A50 to 100 ppm
• B200 to 400 ppm
• C500 to 800 ppm
• D800 to 1,200 ppm

A commercial pool test reveals a Cyanuric Acid (CYA) level of 130 ppm. What operational issue does this high CYA level cause, and what is the proper corrective action?

• AChlorine lock (reduced disinfection rate); partial drain and refill with fresh water
• BSevere plaster corrosion; add calcium chloride
• CHigh total alkalinity; add sodium bisulfate
• DRapid chlorine degradation under sunlight; add stabilized trichlor

What are the typical available chlorine percentage and pH level of commercial liquid pool shock (Sodium Hypochlorite)?

• A90% available chlorine / pH 2.8 to 3.0
• B65% available chlorine / pH 11.8
• C10% to 12.5% available chlorine / pH 11 to 13
• D56% available chlorine / pH 6.7

What secondary chemical parameter increases continuously over time when a pool is sanitized exclusively with Calcium Hypochlorite (Cal-Hypo)?

• ACyanuric acid
• BCalcium Hardness
• CTotal Dissolved Solids only
• DTotal Alkalinity

A technician uses Trichlor-s-triazinetrione (Trichlor) 3-inch tablets in an erosion feeder. What effect does continuous Trichlor feeding have on pool water pH and Cyanuric Acid levels?

• ARaises pH and lowers Cyanuric Acid
• BLowers pH and raises Cyanuric Acid
• CMaintains neutral pH and has zero effect on Cyanuric Acid
• DRaises pH and raises Cyanuric Acid

Which chemical sanitizer features a nearly neutral pH (6.5 to 6.8), dissolves rapidly without clouding water, and adds both free available chlorine and cyanuric acid to pool water?

• ASodium Dichlor-s-triazinetrione (Dichlor)
• BSodium Hypochlorite
• CCalcium Hypochlorite
• DLithium Hypochlorite

Swimmers complain of severe eye burning and a heavy 'chlorine smell' at an indoor public pool. Testing reveals Free Chlorine is 1.0 ppm and Total Chlorine is 2.5 ppm. What is causing the odor and eye irritation?

• AExcessive free available chlorine level in the pool
• BHigh concentration of combined chloramines (1.5 ppm)
• CLow pH level below 6.0
• DHigh cyanuric acid level exceeding 150 ppm

When performing a water test, the pH reagent indicates a high pH of 8.2. What water testing procedure is performed next using titrating drops to determine the exact quantity of acid required to reduce pH to 7.5?

• ABase Demand Test
• BAcid Demand Test
• CCalcium Hardness Titration
• DTotal Alkalinity Neutralization Test

A technician encounters black algae spots firmly rooted in the plaster pores of a concrete swimming pool. What is the most effective treatment protocol?

• AAdd copper sulfate liquid and vacuum immediately
• BVigorously brush spots with a stainless steel wire brush, apply granular Trichlor directl…
• CAdd polyquat algaecide and lower pool water level below spots
• DFlocculate the water using aluminum sulfate without brushing

A swimming pool exhibits chronic water cloudiness, reduced chemical efficacy, and a Total Dissolved Solids (TDS) reading 2,000 ppm above the fill water level. What is the industry accepted corrective action?

• AAdd 10 lbs of sodium bicarbonate
• BSuperchlorinate with 5 gallons of liquid bleach
• CPartially drain and refill the pool with fresh source water of lower TDS
• DFlocculate with alum and backwash twice

Water testing parameters yield: pH 8.0, Temp 84°F (TF 0.7), Calcium 400 ppm (CF 2.2), Alkalinity 150 ppm (AF 2.2), TDS <1000 (TDSF 12.1). Calculating LSI: LSI = 8.0 + 0.7 + 2.2 + 2.2 - 12.1 = +1.0. What physical condition will occur in the pool?

• ASevere plaster etching and heater copper pipe dissolution
• BHeavy calcium carbonate scale formation on pool walls, tile line, and heater heat exchang…
• CImmediate chlorine dissipation due to UV sunlight
• DRapid drop in total alkalinity

Water testing yields: pH 7.0, Temp 60°F (TF 0.4), Calcium 100 ppm (CF 1.6), Alkalinity 60 ppm (AF 1.8), TDS <1000 (TDSF 12.1). LSI = 7.0 + 0.4 + 1.6 + 1.8 - 12.1 = -1.3. What corrective chemical treatments are needed to restore balance?

• AAdd muriatic acid to lower pH and alkalinity
• BAdd sodium carbonate (soda ash) to raise pH, sodium bicarbonate to raise alkalinity, and…
• CAdd cyanuric acid and liquid bleach
• DDrain 50% of pool volume

In a salt chlorine generator system, what chemical byproduct produced alongside chlorine gas at the electrolytic cell causes pool pH to gradually drift upward over time?

• AHydrochloric acid (HCl)
• BSodium Hydroxide (NaOH)
• CCalcium Carbonate (CaCO3)
• DSulfuric Acid (H2SO4)

When collecting a pool water sample for chemical testing, at what depth and location should the water sample container be submerged?

• ADirectly in front of a return jet at a depth of 2 inches
• BInside the skimmer bucket well while the pump is running
• CAt least 18 inches below the water surface, elbows deep, in an area away from return inle…
• DFrom the main drain hydro line outlet at the filter pad