22 Testing, Maintenance & Troubleshooting Practice Questions & Answers

1. 1. An operator is drawing a routine chlorine and pH sample from a commercial pool. Which sampling method gives the most representative picture of the water the bathers are actually in?

   • A.Take the sample at the water surface directly in front of a return inlet, because that water has just come through the filter and the feeder.
   • B.Take the sample about elbow depth in an area of good circulation, well away from return inlets and skimmers, and test it at once.✓ Answer
   • C.Take the sample from inside the skimmer throat, because every bit of surface water passes that point on its way to the pump strainer.
   • D.Take the sample at the shallow-end steps and let it stand in the sun for half an hour so the reagents react at a stable temperature.

   A representative sample comes from the body of water bathers occupy: below the surface, in a well-mixed area, and away from any point where treated water is entering or leaving. Sampling in front of a return is the tempting error because it feels like the cleanest water, but it reads the feeder's output rather than the pool, and it can hide a low residual in the far corners. Chlorine also degrades in a warm, sunlit sample bottle, so the test is run immediately, not after the sample has stood.

   Source: PHTA Pool & Spa Operator Handbook, guidance on collecting a representative water sample for chemical testingReport a problem with this question

2. 2. A facility's kit uses orthotolidine (OTO) reagent only. The operator wants to know whether chloramines are building up. What can that kit report?

   • A.It gives combined chlorine directly, so free chlorine is obtained by subtracting that reading from a total chlorine test.
   • B.It gives free and combined chlorine together, because the yellow deepens toward orange as chloramines accumulate.
   • C.It gives free chlorine as a yellow reading, and combined chlorine is found by adding a second reagent to that same sample.
   • D.It gives total chlorine as a single yellow reading, so free and combined chlorine cannot be separated without a DPD or FAS-DPD kit.✓ Answer

   OTO develops a yellow colour with all oxidized chlorine species at once, so it reports total chlorine and nothing else. The tempting answer is that OTO reads free chlorine, because operators habitually call whatever the kit shows 'the chlorine reading'; but if OTO is treated as free chlorine, a pool loaded with chloramines looks well sanitized when its free residual may be near zero. Separating free from combined requires DPD chemistry, where free chlorine is read first and total chlorine after a further reagent.

   Source: PHTA Pool & Spa Operator Handbook, comparison of OTO and DPD chlorine test chemistriesReport a problem with this question

3. 3. A DPD test on one sample reads free chlorine 2.4 ppm; the total chlorine test on that same sample reads 3.0 ppm. What should the operator record as combined chlorine, and why?

   • A.0.6 ppm, because combined chlorine is what is left when the free reading is subtracted from the total reading.✓ Answer
   • B.5.4 ppm, because the free and total readings are added together to give the whole combined chlorine load in the water.
   • C.2.4 ppm, because the free chlorine reading is itself the chloramine fraction measured by the DPD reagent.
   • D.3.0 ppm, because the total chlorine reading represents the chloramines formed since the last shock treatment.

   Total chlorine is free chlorine plus combined chlorine, so combined chlorine is always the total minus the free: 3.0 minus 2.4 leaves 0.6 ppm. Adding the two readings is the classic slip, and it is tempting because both numbers came off the same kit and feel like separate quantities; but the total test measures everything the free test measured and then some, so adding double-counts the free residual and grossly overstates the chloramines.

   Source: PHTA Pool & Spa Operator Handbook, relationship among free, combined and total chlorine in DPD testingReport a problem with this question

4. 4. After a heavy shock treatment the operator runs a DPD comparator test; the sample flashes pink and then turns clear within a few seconds. What is happening, and what is the right response?

   • A.Very high chlorine has oxidized the DPD dye, so the sample is diluted with chlorine-free water, retested, and the result multiplied back.✓ Answer
   • B.The comparator cell was rinsed in tap water, so rinsing it three times in pool water and running the test again will give a stable colour.
   • C.The reagent has aged past its useful life and lost colour strength, so a fresh bottle of the same reagent should be opened and the test repeated.
   • D.The residual really is at zero, so the reading should be logged as zero and more oxidizer added before bathers are allowed back into the water.

   A momentary pink that fades to clear is bleach-out: chlorine well above the range of the comparator destroys the DPD dye it just coloured. The dangerous mistake is to read the clear cell as zero and add still more oxidizer, which is exactly the wrong direction and can put bathers into a badly overchlorinated pool. Diluting the sample with chlorine-free water brings the residual inside the comparator's range, and multiplying by the dilution factor recovers the true value.

   Source: PHTA Pool & Spa Operator Handbook, discussion of DPD bleach-out at high chlorine residuals and sample dilutionReport a problem with this question

5. 5. Right after superchlorinating a pool, an operator runs a phenol red pH test and the sample turns deep purple. How should that reading be handled?

   • A.The purple is a true pH above the top of the scale, so acid is added at once to bring the water back down where it belongs.
   • B.The purple is the result of overfilling the cell, so pouring off part of the sample and reading it again gives the correct pH.
   • C.The purple is chlorine interference with the indicator, so a neutralizer is added or the residual is allowed to fall before pH is read again.✓ Answer
   • D.The purple is a sign that total alkalinity has climbed too high, so bicarbonate is now buffering the sample against change.

   Phenol red is oxidized by high chlorine, which throws the colour toward purple and can also bleach it out entirely, so the reading is an artifact of the residual rather than a measurement of pH. Treating the purple as a genuinely high pH is the tempting error, and acting on it means dosing acid the water may not need, which drags pH and alkalinity down together. Removing the chlorine interference first, or simply waiting for the residual to fall, gives a pH the operator can act on.

   Source: PHTA Pool & Spa Operator Handbook, note on chlorine interference with the phenol red pH indicatorReport a problem with this question

6. 6. Why might an operator switch from a colour comparator to an FAS-DPD titration when checking chlorine in a pool that has just been shocked?

   • A.The titration reports pH and chlorine from one sample, so both questions are answered in a single step during heavy bather loads.
   • B.The titration measures oxidation-reduction potential instead of concentration, so the strength of the sanitizer is reported directly in millivolts.
   • C.The titration strips cyanuric acid interference out of the sample, so a stabilized pool reads as though no stabilizer were present at all.
   • D.The titration counts drops to a colour endpoint, so it stays readable at high residuals and resolves small increments of combined chlorine.✓ Answer

   In an FAS-DPD titration the result is the number of drops needed to discharge the pink colour, so there is no comparator range to overshoot and no bleach-out at shock-level residuals, and the drop increment resolves combined chlorine finely enough to judge whether breakpoint has been reached. The tempting distractor is the claim about cyanuric acid: stabilizer does distort ORP-based readings, but no field titration removes it from the sample, and cyanuric acid is measured by its own turbidity test.

   Source: PHTA Pool & Spa Operator Handbook, description of FAS-DPD titration for precise free and combined chlorine measurementReport a problem with this question

7. 7. A test kit is running low on reagent, and a bottle of the same-named reagent from a different manufacturer's kit is sitting on the shelf. Why should the operator not use it?

   • A.Reagents of the same name are chemically identical between brands, so the only real issue is that dropper tips deliver different drop sizes.
   • B.Each maker formulates reagents for its own comparator standards and sample volume, so a substituted bottle gives readings that cannot be trusted.✓ Answer
   • C.Substituting a brand cancels the health department's approval of the kit, and that paperwork problem is the only reason the practice is discouraged.
   • D.Reagents from different kits react violently with one another and release chlorine gas, which makes running the test itself dangerous.

   Reagent strength, drop volume and the printed colour standards of a kit are designed as one matched system, so a bottle from another kit can shift the developed colour without any change in the water and the operator has no way to know which readings are real. The tempting distractor is that same-named reagents are interchangeable and only drop size differs; drop size is indeed one of the variables, but concentration and the comparator standards vary too, and a reading that cannot be trusted is worse than no reading at all.

   Source: PHTA Pool & Spa Operator Handbook, instructions on test kit reagents, drop size and comparator standardsReport a problem with this question

8. 8. At one facility the reagent bottles are kept in a clear box on a pump-room shelf above the heater, and none of them are dated. What is the operational consequence?

   • A.Heat and light degrade the reagents, and with no date on the bottles a drifting reading cannot be traced to the water or to the reagent.✓ Answer
   • B.Reagent chemistry stays stable indefinitely once sealed, so the only real requirement is that bottles stand upright to protect the dropper tips.
   • C.Storing reagents warm affects only the pH reagents, so chlorine results stay valid and the pH block alone needs checking against a laboratory.
   • D.Warm reagents react faster and give a stronger colour, so readings will run high until the bottles are replaced each spring at opening.

   Test reagents are light- and heat-sensitive chemicals with a limited shelf life, so a warm sunlit shelf shortens that life and an undated bottle destroys the operator's ability to troubleshoot: when a result drifts, there is no way to rule the reagent in or out. The tempting distractor is that degraded reagents simply read high; degradation is not reliably one-directional, so an operator who assumes a consistent bias will correct readings in the wrong direction. Reagents belong in a cool dark place, dated on receipt and replaced on a set schedule.

   Source: PHTA Pool & Spa Operator Handbook, requirements for test kit reagent storage, dating and replacementReport a problem with this question

9. 9. Two nearby facilities are told to test free chlorine and pH at different minimum frequencies. What governs how often a commercial pool operator must test, and what does the operator then do?

   • A.The code having jurisdiction sets the minimum frequency; the operator meets it, tests more often at peak load, and logs every result.✓ Answer
   • B.The schedule printed in the handbook sets the frequency; the operator follows it as written because it overrides what the local inspector asks.
   • C.The automated controller sets the frequency; the operator relies on its continuous readings and hand-tests only when the controller alarms.
   • D.The chemical supplier's service contract sets the frequency; the operator tests on the visits scheduled in it and keeps the company's reports.

   Testing frequency is a regulatory requirement, and the code having jurisdiction is what sets the minimum, which is why two pools a few miles apart can be held to different schedules; the operator's job is to meet that minimum, exceed it when bather load or weather make the water less stable, and record every result. The tempting distractor is leaning on the automatic controller: a controller drifts and must itself be checked against a manual kit, so its readings supplement the operator's testing rather than replace it.

   Source: CDC Model Aquatic Health Code, operator monitoring and recordkeeping provisions, as applied through the code having jurisdictionReport a problem with this question

10. 10. A health department is investigating a cluster of illnesses among swimmers who used a pool three weeks ago. Which facility records will best answer the investigator's questions?

    • A.The admission receipts and daily head count, which show how many bathers were in the water on each of the days under investigation.
    • B.The manufacturer's manuals for the pump, filter and feeder, which show the equipment was installed to specification when the pool was built.
    • C.The dated logs of free and combined chlorine, pH and temperature, with the time and tester's initials, plus the contamination-incident entries for those days.✓ Answer
    • D.The chemical invoices and delivery tickets for that month, which show what products were on hand and how much of each was purchased.

    An illness investigation asks what the water was actually doing on specific days and whether anything contaminated it, so the chemical log with dates, times and initials plus the contamination-incident record is the evidence that answers it; it is also the operator's own defence, because a complete log can show the water was maintained. Attendance figures are the tempting choice since they identify who was exposed, but they say nothing about disinfection and cannot rule the pool in or out as the source.

    Source: CDC Healthy Swimming guidance for aquatic staff on contamination-incident and water-quality recordkeepingReport a problem with this question

11. 11. An operator finds three growths in a plaster pool: a free-floating green cloud, a powdery yellow film on a shaded wall, and dark raised spots set into the plaster. Which identification is correct?

    • A.Green algae floats in the water, mustard algae dusts shaded walls and brushes off, and black algae roots into the plaster.✓ Answer
    • B.Green algae is the dead-algae haze left after shocking, mustard algae is scale, and black algae is iron deposited on the plaster.
    • C.Green algae grows only on walls, mustard algae floats in suspension, and black algae is a stain left behind by dissolved copper.
    • D.Green algae is pollen floating on the surface, mustard algae is filter media blown back through a return, and black algae is a manganese stain.

    The three growths are told apart by where they sit and how they behave: green algae is free-floating and turns the whole body of water, mustard algae collects as a loose powder on shaded surfaces and lifts with light brushing only to resettle, and black algae anchors into the plaster with a protective cap so it stands proud of the surface. The tempting distractor calls the dark spots a metal stain; a copper or manganese stain lies flat in the surface, cannot be brushed off, and does not grow back in the same spots after treatment.

    Source: PHTA Pool & Spa Operator Handbook, identification of green, mustard and black algae in pools and spasReport a problem with this question

12. 12. A pool holds a normal free chlorine reading at the sample point every morning, yet algae keeps returning on one shaded wall behind the ladder. What is the most likely explanation?

    • A.Circulation is poor in that corner, so chlorine measured in the main body of water never reaches the wall where algae grows.✓ Answer
    • B.The reading is falsely high because the DPD reagent also reacts with algae cells and adds colour that is not chlorine at all.
    • C.Algae are unaffected by any chlorine level, so a residual has no bearing on whether growth appears on a wall in the shade.
    • D.Shade lowers the water temperature at that wall, and cold water blocks chlorine from dissolving into the plaster surface.

    A chlorine reading describes only the water at the sample point, so a dead spot behind a ladder or in a shaded corner can sit with almost no residual while the main body of water tests fine; that is why persistent local algae is a circulation problem before it is a chemistry problem, and why brushing and redirected inlets are part of the cure. The tempting distractor blames the reagent, but DPD does not read algae as chlorine; over-stabilization is a separate reason a normal residual can kill slowly, and it is checked with the cyanuric acid test.

    Source: PHTA Pool & Spa Operator Handbook, discussion of circulation dead spots and localized algae growthReport a problem with this question

13. 13. Black algae keeps coming back in the same spots on a plaster pool even after repeated shocking. Why does it resist treatment, and what does brushing accomplish?

    • A.Its dark colour absorbs sunlight and burns off the chlorine locally, and brushing spreads the spots thin so the sun is no longer focused.
    • B.Its cells settle into the deepest water where the oxidizer never mixes, and brushing lifts them into circulation so the filter can strain them out.
    • C.Its layered cap and its roots in the plaster shield the cells, and brushing tears that cap open so the oxidizer can reach underneath.✓ Answer
    • D.Its growth feeds on the calcium in the plaster rather than on nutrients, and brushing scrapes that calcium away so the colony is starved out.

    Black algae builds a tough protective layer over itself and sends anchoring growth into porous plaster, so an oxidizer added to the water simply never contacts the living cells; mechanical brushing, with a stiff brush suited to the surface, breaks that barrier and is what makes the chemical work. The tempting distractor treats brushing as a way to get the growth into the filter, which is a fair description of loose mustard algae but not of black algae, whose colonies stay anchored and regrow from the same spots.

    Source: PHTA Pool & Spa Operator Handbook, treatment of black algae in plaster surfaces by brushing and oxidationReport a problem with this question

14. 14. A pool has stayed hazy for a week. Chlorine and pH are in range and the water has been shocked twice. What should the operator check next, and in what order?

    • A.Shock a third time at double the dose, because repeated oxidation is what finally clears a haze that has not responded to two treatments.
    • B.Filtration and circulation first: filter pressure against the recorded clean reading, run time and turnover, and only then calcium and alkalinity.✓ Answer
    • C.Add a clarifier every day until the haze lifts, since the particles are too fine for any filter and only coagulation can remove them.
    • D.Drain a quarter of the pool and refill it, because haze that survives shocking is always caused by dissolved solids in the source water.

    Cloudiness that survives correct chemistry is usually a matter of particles not being removed: a filter past its clean pressure, too little run time to turn the water over, a return that is short-circuiting, or scale-forming balance putting calcium into suspension. Troubleshooting therefore goes from the cheapest and most likely cause outward, checking the filter and circulation before dosing anything. Shocking again is the tempting move because it is easy, but an oxidizer cannot remove particles the filter is failing to catch.

    Source: PHTA Pool & Spa Operator Handbook, troubleshooting sequence for persistent cloudy waterReport a problem with this question

15. 15. A brown stain has appeared on the plaster floor of a pool. Which simple field check separates an organic stain from a metal stain?

    • A.Warm the water several degrees for a day: a metal stain dissolves back into solution, while an organic stain darkens as the water heats.
    • B.Brush the spot with a nylon brush: an organic stain will not move at all, while a metal stain wipes away entirely with one light pass.
    • C.Hold a magnet against the stain through the water: a metal stain pulls on the magnet, while an organic stain gives no attraction at all.
    • D.Hold a chlorine tablet on the spot: an organic stain lightens, while a metal stain is unmoved and responds instead to ascorbic acid.✓ Answer

    Organic staining from leaves, algae or other debris is oxidizable, so holding a chlorine tablet against it lightens the spot within a few minutes, while a metal stain is unaffected by an oxidizer and instead fades under ascorbic acid, which reduces the metal back into solution. The tempting distractor is the magnet, since iron is the metal operators picture first; but the iron in a stain is a chemically bound compound, not free metal, so it is not magnetic and the test proves nothing.

    Source: PHTA Pool & Spa Operator Handbook, field identification of organic versus metal staining on pool surfacesReport a problem with this question

16. 16. A crusty grey-white deposit is forming at the waterline and the heater is losing efficiency as flow through it drops. Which water condition explains both, and which way must it be moved?

    • A.The cyanuric acid is high, so stabilizer is precipitating on cool surfaces; draining and diluting the pool is the way to remove the hard crust.
    • B.The saturation index is positive, so calcium is depositing on tile and inside the exchanger; lowering pH or alkalinity moves the index back.✓ Answer
    • C.The combined chlorine is high, so chloramines are plating out at the waterline; breakpoint chlorination will clear the tile and the heater alike.
    • D.The saturation index is negative, so the water is dissolving the exchanger tubes; adding calcium chloride will drive the deposit off the tile.

    Scale is what over-saturated water does: when the saturation index runs positive, calcium carbonate comes out of solution on the surfaces it contacts, which is the crust at the waterline and the coating inside the heat exchanger that insulates it and restricts flow. Bringing pH or total alkalinity down moves the index back toward balance and stops further deposition. The tempting distractor is the negative index, which is the same water-balance idea pointed the wrong way: aggressive water etches plaster and corrodes metal instead of building deposits.

    Source: PHTA Pool & Spa Operator Handbook, saturation index and its relationship to scale formation and heater performanceReport a problem with this question

17. 17. A district runs three pools: one plaster, one vinyl-lined and one fiberglass. How should brushing and cleaning tools be matched to those surfaces?

    • A.Brush choice follows the algae rather than the surface, so any wall carrying black algae is scrubbed with a stainless brush and an abrasive pad.
    • B.Nylon bristles are used on plaster only, while vinyl and fiberglass need stainless bristles to cut through the film that forms on smooth walls.
    • C.Stainless bristles are used on plaster only, while vinyl and fiberglass are brushed with nylon and cleaned without abrasive pads.✓ Answer
    • D.Stainless bristles are safe on all three, since the bristle is softer than any pool surface and only lifts loose growth off the wall.

    Tool selection follows the hardness of the finish: stainless bristles are aggressive enough for a hard plaster or exposed-aggregate surface, while a vinyl liner tears and a fiberglass gel coat scratches and dulls, so those surfaces get nylon and no abrasive pads. The tempting distractor makes the brush follow the algae, which is understandable because black algae genuinely needs aggressive brushing; but a stainless brush taken to a liner will open a leak that costs far more than the algae did.

    Source: PHTA Pool & Spa Operator Handbook, matching brushes and cleaning methods to plaster, vinyl and fiberglass surfacesReport a problem with this question

18. 18. After treating a heavy algae bloom, an operator vacuums the settled debris to waste instead of through the filter. What has to be managed while that is being done?

    • A.The circulation pump has to be switched off while vacuuming, since the debris is drawn out by gravity through the main drain to the waste line.
    • B.The water level has to be watched and topped up so the pump keeps its prime, and the make-up water dilutes the residual, so chemistry is retested.✓ Answer
    • C.The sanitizer should be raised to shock level as the vacuuming runs, so that debris passing down the waste line is disinfected on its way out.
    • D.The filter must be backwashed first so the waste line runs clear, and the heater should be fired during vacuuming to hold the temperature steady.

    Vacuuming to waste sends water out of the system instead of returning it, so the level drops fast; if it falls below the skimmer the pump takes air, loses prime and can be damaged, and the fresh water added to replace it dilutes sanitizer, stabilizer and hardness, which is why a full test and adjustment follows the job. The tempting distractor is shutting the pump off, which confuses vacuuming to waste with gravity draining; the vacuum head works because the pump is running and pulling suction.

    Source: PHTA Pool & Spa Operator Handbook, procedure for vacuuming to waste after an algae treatmentReport a problem with this question

19. 19. Cyanuric acid has climbed well above the level an operator wants to work at, and stabilized tablets have been the pool's only chlorine source. What actually lowers it?

    • A.Raising free chlorine to shock level burns it off, in the same way that breakpoint chlorination destroys combined chlorine in a pool.
    • B.Adding a sequestering agent binds it up, the same way a sequestrant handles dissolved metals so that they no longer cause staining.
    • C.Backwashing the sand filter strips it out of the water, because the stabilizer is held on the media and leaves with the backwash flow.
    • D.Replacing part of the water with fresh fill dilutes it, and switching to an unstabilized chlorine keeps it from climbing straight back.✓ Answer

    Cyanuric acid is not consumed by chlorination, does not evaporate and is not filtered out, so the only routine way to reduce it is to remove water containing it and replace that water with fill water containing none; the concentration falls in proportion to the fraction replaced. Because stabilized tablets keep adding more with every ounce of chlorine, the dilution has to be paired with a switch to an unstabilized product or the level simply climbs again. Shocking is the tempting answer by analogy with chloramines, but shock oxidizes combined chlorine, not stabilizer.

    Source: PHTA Pool & Spa Operator Handbook, management of cyanuric acid accumulation and reduction by dilutionReport a problem with this question

20. 20. A spa throws up a persistent head of foam whenever the jets run. Which combination of water conditions best explains it?

    • A.Free chlorine has fallen to zero while pH has risen, so bacteria in the plumbing are the only thing able to generate lasting foam.
    • B.Water temperature has dropped below the set point with the blower off, so trapped air is the sole source of the standing foam.
    • C.Calcium hardness has climbed high while alkalinity has fallen, so the water has turned scale-forming and feels slick around the jets.
    • D.Calcium hardness has fallen low while soaps, lotions and dissolved solids build up in a small, heavily used volume of water.✓ Answer

    Foam is a surface-tension problem: soft water plus the surfactants bathers carry in, concentrated in the small volume of a heavily used spa and whipped by the jets, holds bubbles that would otherwise break. The cure is to restore calcium hardness and to dilute or replace the loaded water, along with pre-shower rules for bathers. The tempting distractor blames high hardness, because operators associate hardness problems with spas; but high calcium produces scale and cloudiness, not a standing head of foam.

    Source: PHTA Pool & Spa Operator Handbook, causes of foaming in spas including low calcium hardness and bather-introduced surfactantsReport a problem with this question

21. 21. A busy spa needs acid almost daily, its chlorine demand swings from hour to hour, and dissolved solids keep climbing even though every chemical is dosed correctly. What does this pattern call for?

    • A.The feed pump has drifted out of calibration, so recalibrating the controller against a manual test kit will bring demand back into line.
    • B.The filter media is exhausted, so replacing the sand and putting the spa back into service will settle the readings within a couple of days.
    • C.The water has reached the end of its useful life for that bather load, so the spa is drained, the shell and filter cleaned, and it is refilled.✓ Answer
    • D.The heater is running above its set point, so lowering the water temperature will stop the swings without any need to touch the water itself.

    A spa holds a small volume against a very large bather load, so body oils, dissolved solids and spent chemical by-products concentrate until the water no longer responds predictably to dosing: readings swing, acid demand rises and nothing holds. At that point the answer is water replacement, together with cleaning the shell and the filter where the accumulated film lives. The tempting distractor is recalibrating the feeder, which is good practice in general but cannot fix water whose carrying capacity is exhausted.

    Source: PHTA Pool & Spa Operator Handbook, guidance on spa water replacement based on bather load and accumulated dissolved solidsReport a problem with this question

22. 22. A pool in a hard-freeze climate is being closed for the winter. What is the operating principle behind the closing procedure?

    • A.Cold water holds chlorine longer than warm water, so the pool is shocked to a high residual and left full to carry the sanitizer through the winter.
    • B.Water standing in pipes, pump and filter expands as it freezes, so those volumes are lowered, blown clear and plugged before the freeze arrives.✓ Answer
    • C.Ice on the surface protects the shell from the cold, so the pool is filled to the top of the tile and the circulation is left running all season.
    • D.Freezing kills the algae spores held in the plaster, so the pool is left uncovered and untreated and is simply brushed and refilled in the spring.

    Water expands as it turns to ice, and expansion inside a closed pipe, pump volute or filter tank has nowhere to go, so it splits fittings and cracks housings; the whole closing procedure exists to remove or displace that trapped water by lowering the level below the returns, blowing the lines clear, plugging them, and draining the equipment. The tempting distractor leaves the pool full and running, which does prevent freezing while power and flow hold, but a single pump failure or outage in a hard freeze then destroys the plumbing.

    Source: PHTA Pool & Spa Operator Handbook, winterizing procedures for pools in freezing climatesReport a problem with this question

Practice questions based on the Pool & Hot Tub Alliance (PHTA) Pool & Spa Operator Handbook and public CDC healthy-swimming guidance. CPO and Certified Pool/Spa Operator are marks of the Pool & Hot Tub Alliance; this site is not affiliated with or endorsed by PHTA. Water-quality limits, turnover requirements and bather loads are set by the health code where your facility operates — always follow that code and your local health department, and confirm current course requirements before testing. About the CPO certification →