CPO EXAM | CERTIFIED POOL
OPERATOR EXAM STUDY GUIDE | 100%
CORRECTLY ANSWERED AND RATED
A+ | 2025/2026 GUIDE
What is the difference between hard water and soft water?
-Correct Answer-Hard water will produce scaling resulting in mineral
deposits on wall or in pipes.
Soft water is too low in hardness and readily foams and will cause
corrosion.
What is acceptable Calcium hardness values ____ to ___?
How often should it be tested for main pool _____?
How often should it be tested in spas _____?
-Correct Answer-150-400 ppm
Main pool: 1x a week
Spa: Daily
If Calcium Hardness is too high what needs to be added?
-Correct Answer-Drain and re-fill pool
,If Calcium Hardness is too low what needs to be added?
-Correct Answer-Calcium chloride
What is TDS?
-Correct Answer-Sum of all organic and inorganic materials dissolved in
water: minerals, salts, sweat, urine, etc.
If TDS levels are too high what 7 thing can it cause?
-Correct Answer-
1. Enhance algae growth
2.Increase natural galvanic corrosion with a high salt content.
3. Accelerate staining and scaling of pool and spa surface
4. Cloudy and dull looking water
5. Foaming
6. Water balance is hard to maintain
7. Reduce sanitizer efficiency by 50%
What is acceptable TDS values: _______?
How often should it be tested?
-Correct Answer-<1500 ppm
Daily
, What is MAXIMUM pool temperatures:
Main Pool
Therapy Pool
Spa
-Correct Answer-
Main or swimming pool: 88 degrees
Therapy Pool: 96 degrees
Spa: 104 degrees
Five primary factors that affect water balance and are incorporated into the
saturation index formula?
-Correct Answer-
1. pH
2. Total Alkalinity
3. Calcium Hardness
4. TDS
5. Temperature
What is the Langelier Saturation Index:
-Correct Answer-pH + CF + AF + TF - 12.1
OPERATOR EXAM STUDY GUIDE | 100%
CORRECTLY ANSWERED AND RATED
A+ | 2025/2026 GUIDE
What is the difference between hard water and soft water?
-Correct Answer-Hard water will produce scaling resulting in mineral
deposits on wall or in pipes.
Soft water is too low in hardness and readily foams and will cause
corrosion.
What is acceptable Calcium hardness values ____ to ___?
How often should it be tested for main pool _____?
How often should it be tested in spas _____?
-Correct Answer-150-400 ppm
Main pool: 1x a week
Spa: Daily
If Calcium Hardness is too high what needs to be added?
-Correct Answer-Drain and re-fill pool
,If Calcium Hardness is too low what needs to be added?
-Correct Answer-Calcium chloride
What is TDS?
-Correct Answer-Sum of all organic and inorganic materials dissolved in
water: minerals, salts, sweat, urine, etc.
If TDS levels are too high what 7 thing can it cause?
-Correct Answer-
1. Enhance algae growth
2.Increase natural galvanic corrosion with a high salt content.
3. Accelerate staining and scaling of pool and spa surface
4. Cloudy and dull looking water
5. Foaming
6. Water balance is hard to maintain
7. Reduce sanitizer efficiency by 50%
What is acceptable TDS values: _______?
How often should it be tested?
-Correct Answer-<1500 ppm
Daily
, What is MAXIMUM pool temperatures:
Main Pool
Therapy Pool
Spa
-Correct Answer-
Main or swimming pool: 88 degrees
Therapy Pool: 96 degrees
Spa: 104 degrees
Five primary factors that affect water balance and are incorporated into the
saturation index formula?
-Correct Answer-
1. pH
2. Total Alkalinity
3. Calcium Hardness
4. TDS
5. Temperature
What is the Langelier Saturation Index:
-Correct Answer-pH + CF + AF + TF - 12.1
