Practice Test Geeks(CPI) Certified Pool & Spa Inspector Practice Test
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Water Quality & Treatment Standards Flashcards

7 cards from real CPI practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.

Read the first 7 Water Quality & Treatment Standards flashcards as text

  1. What is the Langelier Saturation Index (LSI) used to predict in pool water?

    Answer: Whether water will be scale-forming or corrosive

    The LSI predicts whether water is balanced — a positive value indicates scale-forming tendency; a negative value indicates corrosive tendency.

  2. At what pH level does hypochlorous acid (the active sanitizing form of chlorine) exist in its highest concentration?

    Answer: 7.2–7.4

    At pH 7.2–7.4, approximately 75–80% of chlorine exists as hypochlorous acid, the most effective sanitizing form.

  3. A spa inspector measures the water temperature at 104°F. What is the primary water quality concern at this temperature?

    Answer: Chlorine dissipates much faster requiring more frequent dosing

    Elevated spa temperatures dramatically accelerate chlorine dissipation, requiring more frequent monitoring and dosing to maintain safe sanitizer levels.

  4. What does a 'total dissolved solids' (TDS) reading above 1,500 ppm above the source water baseline typically indicate?

    Answer: Water needs to be partially drained and replaced

    High TDS (>1,500 ppm above fill water) means dissolved minerals and chemicals have accumulated to a level requiring partial drain and refill.

  5. Which type of algae is hardest to treat and typically requires brushing plus a specialized algaecide or high-dose chlorine shock?

    Answer: Black algae

    Black algae embeds its roots into plaster and grout, making it very difficult to eradicate and requiring aggressive brushing and high chlorine levels.

  6. When using sodium dichloro-s-triazinetriene (dichlor) as a sanitizer, what secondary effect must inspectors be aware of?

    Answer: It increases cyanuric acid levels with each application

    Dichlor is a stabilized chlorine product; repeated use steadily increases cyanuric acid levels, which can eventually impair chlorine effectiveness.

  7. What is the purpose of a 'phosphate remover' product in pool water treatment?

    Answer: Remove algae nutrients that promote algae growth

    Phosphates are a primary nutrient source for algae; removing them helps prevent algae blooms and reduces chlorine demand.