Pool Chemistry Certified-residential Exam
Questions and Answers
- 1.
UV (ultraviolet) light is used for disinfection and combined chlorine removal.
- A.
True
- B.
False
Correct Answer
A. TrueExplanation
UV light is commonly used for disinfection purposes because it has the ability to kill or inactivate microorganisms, such as bacteria and viruses, by damaging their DNA or RNA. This makes it an effective method for sterilizing water, air, and surfaces. Additionally, UV light can also help in removing combined chlorine, which is formed when chlorine reacts with organic matter in water. The UV radiation breaks down the combined chlorine compounds, leading to their removal. Therefore, the statement that UV light is used for disinfection and combined chlorine removal is true.Rate this question:
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- 2.
The PCTI recommended Target for Calcium Hardness for plaster pool surfaces is
- A.
250 ppm
- B.
350 ppm
- C.
500 ppm
- D.
150 ppm
Correct Answer
B. 350 ppmExplanation
The PCTI (Plasterers' Craftsmanship Training Institute) recommends a target of 350 ppm (parts per million) for calcium hardness for plaster pool surfaces. Calcium hardness refers to the amount of dissolved calcium in the water, and maintaining it within the recommended range helps prevent issues such as scale formation, etching of plaster surfaces, and corrosion of pool equipment. A higher calcium hardness level can lead to cloudy water and scaling, while a lower level can cause the water to become corrosive. Therefore, 350 ppm is the ideal target to ensure the longevity and proper functioning of plaster pool surfaces.Rate this question:
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- 3.
The PCTI recommended Target for pH is
- A.
7.2
- B.
7.6
- C.
7.5
- D.
7.8
Correct Answer
C. 7.5Explanation
The PCTI (Prescription and Care of the Intensive) recommends a target pH of 7.5. This means that in order to maintain optimal health and functioning, it is recommended to keep the pH level of the body within the range of 7.2 to 7.6. A pH level of 7.5 is considered slightly alkaline, which is believed to support various bodily functions and promote overall well-being.Rate this question:
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- 4.
There are 7 water balance parameters or conditions. They are pH, Total Alkalinity, Calcium Hardness, Temperature and
- A.
TDS, CYA (cyanuric acid), and borate
- B.
TDS, CYA (cyanuric acid), and sulfate
- C.
TDS, CYA (cyanuric acid), and phosphate
- D.
TDS, CYA (cyanuric acid), and carbonate
Correct Answer
A. TDS, CYA (cyanuric acid), and borateExplanation
The correct answer is TDS, CYA (cyanuric acid), and borate. These three parameters are important for maintaining the water balance in a pool or spa. TDS (Total Dissolved Solids) refers to the concentration of all dissolved substances in the water, including minerals, salts, and other impurities. CYA (cyanuric acid) is a stabilizer that helps protect chlorine from degradation due to sunlight. Borate is a pH buffer that helps stabilize the water's pH level. By monitoring and adjusting these parameters, the water can be kept in optimal condition for swimming or soaking.Rate this question:
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- 5.
Ozone (O3) is one of the strongest oxidizers known. It is 25 times more powerful than HOCl, 2500 times more powerful than OCl- and 5,000 times stronger than chloramine.
- A.
True
- B.
False
Correct Answer
A. TrueExplanation
Ozone (O3) is known to be a strong oxidizer, meaning it has the ability to remove electrons from other substances. The statement suggests that ozone is 25 times more powerful than HOCl (hypochlorous acid), 2500 times more powerful than OCl- (hypochlorite ion), and 5000 times stronger than chloramine. This implies that ozone has a significantly higher oxidizing capacity compared to these other substances, making the statement true.Rate this question:
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- 6.
CYA (cyanuric acid) increases the free chlorine requirement needed for controlling bacteria and algae.
- A.
True
- B.
False
Correct Answer
A. TrueExplanation
Cyanuric acid, also known as CYA, increases the amount of free chlorine needed to effectively control bacteria and algae in a pool. This is because CYA acts as a stabilizer for chlorine, preventing it from being rapidly degraded by sunlight. Without CYA, the chlorine would dissipate quickly, requiring more frequent additions of chlorine to maintain proper sanitation levels. Therefore, it is true that CYA increases the free chlorine requirement for controlling bacteria and algae.Rate this question:
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- 7.
Trichlor and dichlor are acidic, have a low pH and will lower the pH and Total Alkalinity of he pool water.
- A.
True
- B.
False
Correct Answer
A. TrueExplanation
Trichlor and dichlor are types of chlorine compounds commonly used in swimming pools. These compounds are acidic in nature and have a low pH. When added to pool water, they can lower the pH level and also reduce the total alkalinity. This is because the compounds release hydrogen ions, which increase the acidity of the water. As a result, the pH level decreases and the total alkalinity is also affected. Therefore, the statement that trichlor and dichlor are acidic and can lower the pH and total alkalinity of pool water is true.Rate this question:
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- 8.
A pool service company has a 20,000 gallon pool with a TA of 40 ppm. The Target TA is 90 ppm. How much Bicarb will be needed to make the change from 40 ppm to 90 ppm? (Use the Easy Dosage Charts beginning on page 97 or the examples on page 100 in Chapter 10 or the Pool Chem Dose App)
- A.
112 oz
- B.
20 lbs
- C.
168 oz
- D.
224 oz
Correct Answer
D. 224 oz -
- 9.
How many gallons of water are there in 1 cubic foot (1 ft3)?
- A.
7.00
- B.
7.48
- C.
8.00
- D.
8.34
Correct Answer
B. 7.48Explanation
One cubic foot is equal to 7.48 gallons of water. This conversion is based on the fact that one gallon is equal to 0.1337 cubic feet. Therefore, to find the number of gallons in one cubic foot, we can multiply 1 by 7.48, resulting in 7.48 gallons.Rate this question:
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- 10.
The minimum calcium hardness needed to balance the water is?
- A.
350 ppm
- B.
250 ppm
- C.
150 ppm
- D.
100 ppm
Correct Answer
C. 150 ppmExplanation
The minimum calcium hardness needed to balance the water is 150 ppm. Calcium hardness refers to the concentration of calcium ions in the water, and it is important to maintain a certain level to prevent corrosion of metal surfaces, such as pipes and fixtures. A calcium hardness level below 150 ppm can lead to the water becoming too soft, which can cause these metal surfaces to deteriorate. Therefore, a minimum calcium hardness of 150 ppm is necessary to ensure water balance and prevent damage.Rate this question:
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- 11.
CYA (Cyanuric Acid) only protects chlorine in water from being degraded by sunlight (UV). It does not do anything else in the water.
- A.
True
- B.
False
Correct Answer
B. FalseExplanation
Cyanuric Acid (CYA) does more than just protect chlorine in water from degradation by sunlight. It acts as a stabilizer for chlorine, helping it last longer in the water and reducing the amount of chlorine needed to maintain proper disinfection levels. CYA also helps to prevent chlorine loss due to evaporation. Therefore, the statement that CYA does not do anything else in the water is incorrect.Rate this question:
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- 12.
The Target level for borate in pool water with no SWG (saltwater chlorine generator) is
- A.
50 ppm
- B.
80 ppm
- C.
30 ppm
- D.
100 ppm
Correct Answer
A. 50 ppmExplanation
The correct answer is 50 ppm. Borate is often added to pool water as a pH buffer and to prevent algae growth. A level of 50 ppm is considered optimal for pool water with no SWG, as it helps maintain the pH balance and inhibits the growth of algae. Higher levels of borate may not provide any additional benefits and can potentially lead to cloudy water or staining.Rate this question:
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- 13.
What is the weight of 1 gallon of water
- A.
8.34 lbs
- B.
8.00 lbs
- C.
7.00bs
- D.
7.50 lbs
Correct Answer
A. 8.34 lbsExplanation
Water has a density of 8.34 pounds per gallon at room temperature. This means that 1 gallon of water weighs 8.34 pounds.Rate this question:
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- 14.
The LSI (Langelier Saturation Index) is based on
- A.
Sodium carbonate saturation
- B.
Calcium carbonate saturation
- C.
Lanthanum carbonate saturation
- D.
Calcium sulfate saturation
Correct Answer
B. Calcium carbonate saturationExplanation
The correct answer is calcium carbonate saturation because the LSI (Langelier Saturation Index) is a measure of the tendency of water to deposit or dissolve calcium carbonate. It is used to determine the scaling or corrosive potential of water in relation to calcium carbonate. By calculating the LSI, one can assess whether the water is under-saturated, balanced, or over-saturated with calcium carbonate, which helps in understanding its scaling or corrosive behavior.Rate this question:
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- 15.
Pouring acid into the water while standing in one place or adding acid in a column into the water will lower only total alkalinity.
- A.
True
- B.
False
Correct Answer
B. FalseExplanation
Pouring acid into the water while standing in one place or adding acid in a column into the water will not only lower total alkalinity. This is because when acid is added to water, it reacts with the alkaline substances present in the water, causing a decrease in alkalinity. However, it can also affect other properties of the water such as pH levels and acidity. Therefore, the statement is false as it does not consider the potential impact on other water properties.Rate this question:
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- 16.
1% is how may ppm?
- A.
100
- B.
10,000
- C.
1,000,000
- D.
1,000
Correct Answer
B. 10,000Explanation
The answer is 10,000 because ppm stands for "parts per million," which is a unit used to express small concentrations of a substance in a solution. 1% is equivalent to 10,000 parts per million, meaning that for every million parts of the solution, 10,000 parts are the substance in question.Rate this question:
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- 17.
Pool water must have a minimum calcium hardness of _______ ppm or it will be aggressive.
- A.
250
- B.
100
- C.
350
- D.
150
Correct Answer
D. 150Explanation
Pool water needs to have a minimum calcium hardness of 150 ppm to prevent it from becoming aggressive. If the calcium hardness is below this level, the water can become corrosive and damage the pool's surfaces and equipment. Having the correct calcium hardness level helps to maintain a balanced and stable pool environment.Rate this question:
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- 18.
The amount of salt needed for most SWGs (salt water chlorine generators) is 3,000 to 3,500 ppm
- A.
True
- B.
False
Correct Answer
A. TrueExplanation
The correct answer is true because most salt water chlorine generators (SWG) require a salt concentration of 3,000 to 3,500 parts per million (ppm) in order to effectively generate chlorine. This concentration is necessary for the SWG to function properly and maintain the desired level of chlorine in the pool water.Rate this question:
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- 19.
With 30 ppm CYA in the water, 97% of all the chlorine in the water is bound to CYA and only 3% of the chlorine is available for killing and oxidizing.
- A.
True
- B.
False
Correct Answer
A. TrueExplanation
With 30 ppm CYA (Cyanuric Acid) in the water, it forms a complex with chlorine, reducing its effectiveness. This means that 97% of the chlorine is bound to CYA, leaving only 3% of the chlorine available for its intended purpose of killing bacteria and oxidizing contaminants. Therefore, the statement is true.Rate this question:
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- 20.
The pH of pool water can be raised by aeration and turbulence with no change in alkalinity.
- A.
True
- B.
False
Correct Answer
A. TrueExplanation
Aeration and turbulence can increase the pH of pool water without affecting its alkalinity. This is because aeration introduces oxygen into the water, which reacts with carbon dioxide to form carbonic acid. This acid then dissociates into hydrogen ions and bicarbonate ions, raising the pH. However, alkalinity is a measure of the water's ability to resist changes in pH, so it remains unaffected by the aeration and turbulence. Therefore, the statement is true.Rate this question:
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- 21.
It is okay to add calcium chloride (hardness increaser) and sodium bicarbonate (baking soda) at the same time to the water.
- A.
True
- B.
False
Correct Answer
B. FalseExplanation
Adding calcium chloride and sodium bicarbonate at the same time to water is not okay because they have opposite effects on water hardness. Calcium chloride increases water hardness by adding calcium ions, while sodium bicarbonate decreases water hardness by adding bicarbonate ions. Adding them together would result in a neutralizing effect and could potentially lead to an imbalance in water chemistry. Therefore, it is not recommended to add them simultaneously.Rate this question:
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- 22.
Buffers prevent, inhibit or slow down pH change due to small amounts of acid or base.
- A.
True
- B.
False
Correct Answer
A. TrueExplanation
Buffers are substances that help maintain the pH of a solution by resisting changes in acidity or alkalinity. They achieve this by accepting or donating protons to prevent the concentration of hydrogen ions from changing significantly. In other words, buffers can neutralize small amounts of added acid or base, preventing drastic changes in pH. Therefore, the statement that buffers prevent, inhibit, or slow down pH change due to small amounts of acid or base is true.Rate this question:
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- 23.
How many days should you wait to add the required amount of salt for an SWG (salt water chlorine generator) in a new plaster pool?
- A.
4days
- B.
45 days
- C.
28 days
- D.
14 days
Correct Answer
C. 28 daysExplanation
In a new plaster pool, it is recommended to wait 28 days before adding the required amount of salt for an SWG. This waiting period allows the plaster to cure properly and prevents any potential damage or discoloration that could occur if salt is added too soon. Waiting for 28 days ensures that the plaster is fully set and ready to withstand the saltwater environment created by the SWG.Rate this question:
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- 24.
If the pH of the pool water is always increasing or going up, lowering the total alkalinity will slow down the rate of increase.
- A.
True
- B.
False
Correct Answer
A. TrueExplanation
Lowering the total alkalinity of the pool water will reduce its ability to resist changes in pH. Therefore, if the pH of the pool water is always increasing, lowering the total alkalinity will slow down the rate of increase as the water will be less resistant to pH changes.Rate this question:
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- 25.
Mixing trichlor with cal hypo will cause a fire and explosion.
- A.
True
- B.
False
Correct Answer
A. TrueExplanation
Mixing trichlor (trichloroisocyanuric acid) with cal hypo (calcium hypochlorite) can indeed cause a fire and explosion. Trichlor is a strong oxidizing agent, and when it comes into contact with cal hypo, which is also an oxidizing agent, a highly reactive and dangerous mixture is created. This combination can release large amounts of heat and oxygen, leading to a fire and potential explosion. It is important to handle these chemicals with caution and avoid mixing them together to prevent any accidents or hazards.Rate this question:
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- 26.
As long as the free chlorine level in the water is between 2.0 and 4.0 ppm, algae cannot grow.
- A.
True
- B.
False
Correct Answer
B. FalseExplanation
This statement is false because algae can still grow even if the free chlorine level in the water is between 2.0 and 4.0 ppm. While maintaining a free chlorine level within this range can help control and prevent algae growth to some extent, it does not completely eliminate the possibility of algae growth. Other factors such as sunlight exposure, nutrient levels, and temperature can also contribute to the growth of algae in water.Rate this question:
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- 27.
A pool service tech has a 16,875 gallon pool with a free chlorine level of 2.0 ppm and CYA of 50 ppm. The Target FC is 7.5% of CYA. The Target is 0.075 × 50 = 3.75 ppm so the tech decides to raise FC by 2.0 ppm. How much liquid chlorine (sodium hypochlorite) 12.5% will he need to add? (Use the Easy Dosage Chart on page 102 in Chapter 10 or the Pool Chem Dose App)
- A.
43.2 floz
- B.
51.5 fl oz
- C.
34.5 fl oz
- D.
30.7 fl oz
Correct Answer
C. 34.5 fl ozExplanation
The target free chlorine level is calculated by multiplying the CYA level by 0.075, which gives a target of 3.75 ppm. Since the current free chlorine level is 2.0 ppm, the technician needs to raise it by 1.75 ppm (3.75 ppm - 2.0 ppm). The liquid chlorine concentration is 12.5%, so to raise the free chlorine by 1.75 ppm, the technician needs to add a certain volume of liquid chlorine. By using the dosage chart or app, it is determined that the technician needs to add 34.5 fl oz of liquid chlorine to achieve the desired level.Rate this question:
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- 28.
The PCTI recommended Target for CYA (cyanuric acid) with no SWG is
- A.
100 ppm
- B.
30 ppm
- C.
70 ppm
- D.
50 ppm
Correct Answer
D. 50 ppmExplanation
The recommended target for cyanuric acid (CYA) without a saltwater chlorine generator (SWG) is 50 ppm. CYA is a stabilizer that helps protect chlorine from being degraded by sunlight. It is important to maintain an appropriate CYA level to ensure effective disinfection and prevent excessive chlorine loss. Too low a CYA level may result in rapid chlorine depletion, while too high a level can reduce chlorine's effectiveness. Therefore, a target of 50 ppm is recommended to strike a balance and optimize chlorine efficiency.Rate this question:
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- 29.
One gallon of liquid chlorine (sodium hypochlorite) 12.5% contains about 1 lb of pure chlorine.
- A.
True
- B.
False
Correct Answer
A. TrueExplanation
Sodium hypochlorite is commonly used as a disinfectant and bleach, and it contains chlorine. The statement is stating that one gallon of liquid chlorine, specifically sodium hypochlorite with a concentration of 12.5%, contains approximately 1 lb of pure chlorine. This means that the chlorine content in the liquid chlorine is about 1 lb, making the statement true.Rate this question:
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- 30.
What percent of chlorine is lost to sunlight in 2 hours with no CYA?
- A.
65%
- B.
30%
- C.
75%
- D.
50%
Correct Answer
C. 75%Explanation
In the absence of cyanuric acid (CYA), chlorine is more susceptible to degradation by sunlight. This is because CYA acts as a stabilizer, protecting chlorine from the harmful effects of UV rays. Without CYA, chlorine can be rapidly broken down by sunlight, resulting in a higher percentage of chlorine loss. Therefore, it can be inferred that 75% of chlorine is lost to sunlight in 2 hours without CYA.Rate this question:
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- 31.
How many gallons are in a pool that measures 30' by 15' with an average depth of 4.5'?
- A.
18,254 gallons
- B.
16,888 gallons
- C.
12,458 gallons
- D.
15,147 gallons
Correct Answer
D. 15,147 gallonsExplanation
The correct answer is 15,147 gallons. To calculate the volume of the pool, we multiply the length (30') by the width (15') by the average depth (4.5'). This gives us a volume of 2025 cubic feet. Since there are 7.48 gallons in a cubic foot, we multiply the volume by 7.48 to get the total number of gallons, which is 15,147 gallons.Rate this question:
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- 32.
Chlorine gas is produced at the positive (+) electrode of an SWG (saltwater chlorine generator).
- A.
True
- B.
False
Correct Answer
A. TrueExplanation
Chlorine gas is produced at the positive electrode of a saltwater chlorine generator. This is because when an electric current is passed through the saltwater solution, a chemical reaction occurs at the positive electrode, known as the anode. This reaction causes chloride ions (Cl-) to lose an electron and form chlorine gas (Cl2). Therefore, it is true that chlorine gas is produced at the positive electrode of an SWG.Rate this question:
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- 33.
Using the pH-Total Alkalinity Adjusting Charts beginning in Chapter 10, Page 103, if a 10,000 gallon pool has a pH of 7.8 and the TA is 110 ppm, what should you do?
- A.
Add Muriatic Acid 51 fl oz Aerate
- B.
Add 26 fl oz of muriatic acid and hen aerate
- C.
Add 15floz of muriatic acid and then add 15 oz of soda ash
- D.
Add 9 oz of bicarb and 11 fl oz of muriatic acid
Correct Answer
A. Add Muriatic Acid 51 fl oz AerateExplanation
Based on the information provided, the correct answer is to add 51 fl oz of muriatic acid and aerate the pool. This is determined by referring to the pH-Total Alkalinity Adjusting Charts in Chapter 10, Page 103, which provides guidance on adjusting pH levels based on the pool's total alkalinity. In this case, with a pH of 7.8 and a TA of 110 ppm, the recommended action is to add muriatic acid to lower the pH, and then aerate the pool to help balance the chemistry.Rate this question:
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- 34.
Adding 25.6 fl oz of muriatic acid (HCl 31.5%) to 10,000 gallons of water will lower total alkalinity by 10 ppm.
- A.
True
- B.
False
Correct Answer
A. TrueExplanation
Adding muriatic acid, which is a strong acid, to water will lower the total alkalinity. The acid reacts with the alkaline compounds in the water, reducing their concentration and thus lowering the alkalinity. Therefore, adding 25.6 fl oz of muriatic acid to 10,000 gallons of water will indeed lower the total alkalinity by 10 ppm.Rate this question:
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- 35.
Indoor pools can benefit from using CYA.
- A.
True
- B.
False
Correct Answer
A. TrueExplanation
The use of CYA (cyanuric acid) in indoor pools can indeed provide benefits. CYA is a stabilizer that helps protect chlorine from being rapidly degraded by sunlight. While indoor pools are not exposed to direct sunlight, CYA can still be beneficial as it helps to maintain a consistent chlorine level and reduces the need for frequent chlorine additions. This can result in cost savings and improved water quality in indoor pools.Rate this question:
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- 36.
Using liquid chlorine or other hypochlorites will raise the pH of the pool water.
- A.
True
- B.
False
Correct Answer
B. FalseExplanation
Using liquid chlorine or other hypochlorites will not raise the pH of the pool water. In fact, these chemicals tend to lower the pH levels. When added to the water, they release hydrogen ions, which decrease the pH and make the water more acidic. To increase the pH, other chemicals like soda ash or sodium bicarbonate need to be added.Rate this question:
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- 37.
The white flakes in a SWG pool are
- A.
High TDS
- B.
Excess salt
- C.
Deposits that were on the SWG plates that came off when the polarity was reversed
- D.
SWG dandruff
Correct Answer
C. Deposits that were on the SWG plates that came off when the polarity was reversedExplanation
The white flakes in a SWG pool are deposits that were on the SWG plates that came off when the polarity was reversed. When the polarity of the SWG (Salt Water Generator) is reversed, it causes a process called electrolysis. This process can cause the deposits that have built up on the SWG plates to loosen and come off, resulting in white flakes in the pool. These flakes are the remnants of the deposits that were on the SWG plates.Rate this question:
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- 38.
The free chlorine level should be _______ % of CYA to kill algae (assumes borate is not being used)
- A.
3%
- B.
7.5%
- C.
4%
- D.
10%
Correct Answer
B. 7.5%Explanation
The correct answer is 7.5%. The free chlorine level should be 7.5% of CYA (Cyanuric Acid) to effectively kill algae in the absence of borate. Cyanuric Acid helps stabilize the chlorine and prevent it from being quickly degraded by sunlight. Maintaining a free chlorine level of 7.5% of CYA ensures that there is enough chlorine present to effectively eliminate algae and maintain a clean and safe swimming pool.Rate this question:
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- 39.
When salt is dissolved in water, ions are formed which are positively and negatively charged like many tiny electrical plates or poles.
- A.
True
- B.
False
Correct Answer
A. TrueExplanation
When salt is dissolved in water, the sodium and chloride ions separate from each other and become surrounded by water molecules. These ions are charged particles, with sodium having a positive charge and chloride having a negative charge. This separation of charges creates an electrical imbalance in the solution, similar to many tiny electrical plates or poles. Therefore, the statement that ions formed when salt is dissolved in water are positively and negatively charged like many tiny electrical plates or poles is true.Rate this question:
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- 40.
1 lb of cal hypo 65% added to 10,000 gallons is about 8.0 ppm
- A.
True
- B.
False
Correct Answer
A. TrueExplanation
When 1 lb of cal hypo 65% is added to 10,000 gallons, it results in a concentration of about 8.0 ppm (parts per million). This means that there are 8.0 parts of cal hypo 65% per million parts of the solution. Therefore, the statement is true.Rate this question:
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- 41.
CO2 in water is in equilibrium with CO2 in the air. Removing CO2 from water will
- A.
Raise pH
- B.
Cannot be done
- C.
Lower pH
- D.
Not change pH
Correct Answer
A. Raise pHExplanation
When CO2 dissolves in water, it forms carbonic acid, which lowers the pH of the water. Removing CO2 from the water will disrupt this equilibrium, causing the concentration of carbonic acid to decrease. As a result, the pH of the water will increase, leading to a higher pH.Rate this question:
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- 42.
Most bromine tabs are BCDMH and contain bromine, DMH and
- A.
Chlorine
- B.
None of the above
- C.
Sodium
- D.
Persulfate
Correct Answer
A. ChlorineExplanation
Bromine tabs are typically made of BCDMH, which stands for bromochloro-5,5-dimethylhydantoin. BCDMH contains both bromine and chlorine, making the answer "chlorine" correct.Rate this question:
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- 43.
2.0 ppm free chlorine in the water with a pH of 7.5 and 30 ppm of CYA (cyanuric acid) will NOT kill algae.
- A.
True
- B.
False
Correct Answer
A. TrueExplanation
The presence of 2.0 ppm free chlorine in the water with a pH of 7.5 and 30 ppm of CYA (cyanuric acid) will not kill algae. The reason for this is that while free chlorine is effective in killing algae, the presence of CYA at 30 ppm inhibits the effectiveness of chlorine. CYA acts as a stabilizer for chlorine, protecting it from degradation by sunlight. However, at high levels like 30 ppm, CYA can also reduce the sanitizing power of chlorine, making it less effective in killing algae. Therefore, even with a sufficient level of free chlorine, the presence of high CYA levels can prevent it from effectively killing algae.Rate this question:
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- 44.
For each 10 ppm of chlorine added by trichlor, how much will CYA increase?
- A.
None
- B.
6ppm
- C.
10 ppm
- D.
3ppm
Correct Answer
B. 6ppmExplanation
Trichlor is a type of chlorine compound that contains cyanuric acid (CYA) as a stabilizer. When trichlor is added to the water, it releases chlorine and also increases the level of CYA. For every 10 ppm of chlorine added by trichlor, the CYA level will increase by 6 ppm. This means that the CYA level increases at a lower rate compared to the chlorine level.Rate this question:
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- 45.
The PCTI recommended Target for Total Alkalinity is
- A.
60 ppm
- B.
120 ppm
- C.
80 ppm
- D.
90 ppm
Correct Answer
D. 90 ppmExplanation
The correct answer is 90 ppm. The PCTI (Pool & Hot Tub Alliance) recommends a target for Total Alkalinity of 90 ppm. Total Alkalinity is a measure of the water's ability to resist changes in pH. Maintaining the alkalinity within the recommended range helps to stabilize the pH levels in the pool or hot tub, preventing fluctuations that could lead to water balance issues or discomfort for swimmers. Therefore, it is important to aim for a Total Alkalinity of 90 ppm to ensure proper water chemistry and a pleasant swimming experience.Rate this question:
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- 46.
Adding borate to the water keeps the pH from going up (pH buffer against pH increase).
- A.
True
- B.
False
Correct Answer
A. TrueExplanation
Adding borate to water can act as a pH buffer, preventing the pH from increasing. Borate ions can react with hydroxide ions, which are responsible for increasing the pH, forming a weak base and water. This reaction helps to maintain the pH at a relatively constant level, making it true that adding borate to water can prevent the pH from going up.Rate this question:
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- 47.
The pH of the pool water usually goes up with a pool equipped with an SWG. This is because
- A.
SWGs produce hydrogen peroxide which raises pH
- B.
SWGs produce carbon dioxide which raises pH
- C.
The hydrogen made gasses off and the bubbles created cause turbulence which raise pH
- D.
SWGs produce liquid chlorine whichhas ahighpH
Correct Answer
C. The hydrogen made gasses off and the bubbles created cause turbulence which raise pHExplanation
The correct answer is that the hydrogen made gasses off and the bubbles created cause turbulence which raises pH. When a pool is equipped with a saltwater chlorine generator (SWG), it produces hydrogen gas as a byproduct. This hydrogen gas then escapes into the air, causing turbulence and the formation of bubbles in the pool water. This turbulence and the presence of bubbles increase the pH of the water, making it more alkaline. Therefore, the pH of the pool water usually goes up with an SWG due to the gassing off of hydrogen and the resulting turbulence.Rate this question:
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- 48.
AOP refers to any number of chemical or electrical processes that use a combination of ozone (O3), hydrogen peroxide (H2O2) and UV to create or maximize production of hydroxyl radicals (●OH) to remove organic matter.
- A.
True
- B.
False
Correct Answer
A. TrueExplanation
The statement is true because AOP (Advanced Oxidation Process) does indeed involve the use of ozone, hydrogen peroxide, and UV to generate hydroxyl radicals. These hydroxyl radicals are highly reactive and can effectively break down and remove organic matter. Therefore, the given statement accurately describes the process of AOP.Rate this question:
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- 49.
Sodium carbonate (soda ash) added to pool water
- A.
Will raise only pH
- B.
Will raise only total alkalinity
- C.
Will raise pH and total alkalinity
- D.
Will raise hardness
Correct Answer
C. Will raise pH and total alkalinityExplanation
When sodium carbonate (soda ash) is added to pool water, it will raise both the pH and total alkalinity levels. Sodium carbonate is a basic compound that acts as a pH increaser. It helps to raise the pH level of the water, making it less acidic. Additionally, sodium carbonate also increases the total alkalinity of the water, which is the measure of its ability to resist changes in pH. Therefore, adding sodium carbonate to pool water will have the effect of raising both the pH and total alkalinity levels.Rate this question:
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- 50.
Changing Temperature by 15°F will change the Langelier Saturation Index (LSI) by
- A.
15
- B.
0.1
- C.
0.2
- D.
0.3
Correct Answer
B. 0.1Explanation
A change in temperature by 15°F will result in a change of 0.1 in the Langelier Saturation Index (LSI). The LSI is a measure of the potential for calcium carbonate to precipitate or dissolve in water. When the LSI is positive, there is a tendency for scale formation, while a negative LSI indicates a tendency for corrosion. A change in temperature affects the solubility of calcium carbonate, which in turn affects the LSI. Therefore, a change of 15°F will cause a small change of 0.1 in the LSI.Rate this question:
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Current Version
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Mar 15, 2023Quiz Edited by
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Apr 10, 2020Quiz Created by
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