Water Balance & Chemical Testing 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 Balance & Chemical Testing flashcards as text
The Langelier Saturation Index (LSI) value of +0.5 indicates pool water is:
Answer: Slightly scale-forming
A positive LSI value indicates supersaturation with calcium carbonate, meaning the water has a tendency to deposit scale on pool surfaces and equipment.
For a spa operating at 104°F, how do recommended free chlorine levels typically compare to a pool at 78°F?
Answer: Higher, because heat accelerates chlorine degradation and pathogen growth
Higher water temperatures accelerate chlorine decomposition and increase microbial activity, so spas generally require more frequent chlorine monitoring and higher minimum residuals.
Which of the following chlorine compounds also contributes to cyanuric acid levels in pool water?
Answer: Trichloro-s-triazinetrione (trichlor)
Trichlor is a stabilized chlorine compound that contains cyanuric acid as part of its chemical structure, adding CYA to the water with each dose.
A pool water sample shows combined chlorine of 0.8 ppm and free chlorine of 1.5 ppm. What does this indicate?
Answer: Significant chloramine formation is present
Combined chlorine above 0.2 ppm indicates significant chloramine buildup, which causes eye irritation and the characteristic 'pool smell.'
What minimum free chlorine concentration is generally required to achieve breakpoint chlorination and destroy chloramines?
Answer: 10 times the combined chlorine level
Breakpoint chlorination requires adding enough chlorine to reach approximately 10 times the combined chlorine level to oxidize and destroy chloramines.
An inspector tests a commercial pool and finds the cyanuric acid level at 200 ppm. The BEST recommendation is to:
Answer: Partially drain and refill the pool to dilute CYA
Excessive cyanuric acid (above 100 ppm in most codes) cannot be chemically removed and requires dilution by partially draining and refilling with fresh water.
Total dissolved solids (TDS) in pool water above 2,000 ppm above the source water level typically causes which issue?
Answer: Reduced effectiveness of pool chemicals and potential corrosion
Elevated TDS interferes with chemical balance, can reduce sanitizer effectiveness, and may lead to equipment corrosion and water that feels heavy or dull.