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Balance practice questions

36 questions from the pool operator (cpo) practice test.

Balance practice test

10 questions, graded as you go, with the reason for every answer. No sign-up.

What this covers

Sample questions

What does total alkalinity measure?

  1. The amount of dissolved calcium and magnesium
  2. The total of all dissolved solids in the water
  3. The water's ability to resist changes in pH
  4. The water's ability to conduct electric current
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C. The water's ability to resist changes in pH

Alkalinity is the buffering capacity that holds pH steady when acids or bases are added. Dissolved calcium and magnesium are hardness, a different measurement.

Reference: PHTA Pool & Spa Operator Handbook, water balance chapter

The pH of a pool swings sharply every time a small amount of chemical is added. Which condition causes this 'pH bounce'?

  1. High total alkalinity
  2. Low calcium hardness
  3. Low total alkalinity
  4. High cyanuric acid
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C. Low total alkalinity

With too little alkalinity there is no buffer, so pH jumps around. High alkalinity causes the opposite problem: pH that is hard to move.

Reference: PHTA Pool & Spa Operator Handbook, water balance chapter

Calcium hardness has climbed far above the recommended range. What is the practical correction?

  1. Add sodium bicarbonate until the hardness drops
  2. Replace some pool water with lower-hardness water
  3. Backwash the filter twice as often for the next two weeks
  4. Superchlorinate to oxidize the excess calcium
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B. Replace some pool water with lower-hardness water

Dissolved calcium is not filtered or oxidized out, so dilution with softer water is the practical way down. Adding bicarbonate would raise alkalinity and make scaling more likely.

Reference: PHTA Pool & Spa Operator Handbook, water balance chapter

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