Pool Cert Flash 4. Chemistry Flashcards
Describe the pH scale?
Measures Acidic to Base on a scale. 0 (acid) - 7 (neutral) - 14 (base)
Pools with volumes over 100,000 gallons and all swimming pools utilizing gas chlorine as a disinfectant are required to have a chemical feeder to control and maintain the pH of the water, T or F?
T
What is the safety for positive displacement pumps used to feed chemicals for pH control?
Chemical feeders must automatically stop when swimming pool recirculation flow is interrupted.
Pools with volumes under 100,000 gallons must also use chemical feeders, but at a lower concentration, T or F?
F. Can be added manually.
How much in ppm will 1.5 pounds of sodium bicarbonate added to 10,000 gallons of water?
10 ppm
How much muriatic acid must be added to 10,000 gallons of water to raise the acid level to 10 ppm
1.6 pints
What causes water hardness to increase?
Dissolved calcium and magnesium compounds.
What can insufficient calcium hardness cause within the pool and system?
Etching of plaster surfaces.
How do you increase water hardness in pools? How much should be added to 10,000 gallons of water to raise the hardness to 80 ppm?
Adding Calcium Chloride. 10 pounds.
What does superchlorination aid in metal effects in water? What levels need to be reached to help this?
Reduce red or brown precipitation stains. 5 to 10 ppm.
Aside from killing bateria growth, what else does the use of Chlorine and Bromine aid in controlling? Which is better?
Algae. Chlorine is better at controlling both bacteria and algae.
How many pounds of Soda Ash must be added per pound of Gas Chlorine to maintain proper pH levels?
1.5 lbs Soda Ash to 1.0 lbs Gas Chlorine
What are the requirements for Chlorine Tanks held in the mechanical room and what safeties must the room maintain?
- The room must be air tight and equipped with mechanical ventilation capable of 1 air change per minute. 2. Chlorine tanks being used must be positioned on individual scales to determine use per day.
How much available chlorine does gas chlorine, liquid chlorine mix solution, granular chlorine contain, and tablet or stick chlorine?
Gas: 100%. Liquid: 10%. Granular: 65% Tablet or Stick: 90%
How is Liquid Chlorine (Sodium Hypochlorite) administered to a pool? What is it’s pH level?
Chemical Metering Pump. 13 pH.
How is Powdered Chlorine (Calcium Hypochlorite) administered to a pool? What is it’s pH?
Mixed with water and injected through the Chemical Metering Pump. 11 pH.
How is Granular Chlorine (Sodium dichloro-isocyanuric acid) administered to a pool? What is it’s pH?
May be dissoced into water and injected into the pool through a Metering Pump. 6.8 pH.
Where are Tablet or Stick Chlrorine (Trichloro-isocyanuric acid) typically used, and how is it administered? What is it’s pH?
Out door pools. Slow dissolving and placed into the Erosion type Feeder. Can’t place in surface skimmers or gutters. 3.0 pH.
How are Bromine Tablets added to pools? How much available bromine and chlorine does it contain? What is it’s pH?
Erosion type Feeder. 61% bromine, 27% chlorine. 4.0 pH.
What is Chlorine Demand, and Bromine Demand?
Amount of the substance required to be added at any time to react against bacteria, dirt and other contaminants.
What is (Free) Residual Chlorine?
Additional amount of the sanitization agent added in anticipation of future contaminants, after the Demand amount is reached.
What is hypochlorous acid and hypochlorite ions, how do they form, and what is their relationship?
Both formed when chlorine is added to the water. In water with a pH of less than 7.5, more hypochlorous acid is formed, which results in more efficient bacteria killing.
What is Combined Residual Chlorine (Chloramines)?
Chlorine available as a bactericide in water, but is combined with another substance (usu. ammonia) to form chloramines. Are much less effective against bacteria.
How do you combat Combined Residual Chlorines?
Increase the chlorine residual to where all of the ammonia is oxidized (Breakpoint - Shock - Superchlorinated). Non-chlorine substances available (Peroxymonosulfate).
The pH of pool water must be maintained between _____ and ____.
7.2 and 7.6 pH
Adding ________ or _________ will raise the pH of the water.
Soda Ash (Sodium Carbonate) or Sodium Hydroxide.
Adding ________ or _________ will lower the pH of the water.
Muriadic Acid (Hydrochloric Acid) or Sodium Bisulfate
The State of Illinois requires the alkalinity of pool water to be b/n ____ and ____ ppm.
50 and 200 ppm
__________ is the most common metal found in water.
Iron
The most common disingectant used to kill bacteria in swimming pools is ________.
Chlorine
Chlorine is available in these three forms:
- Gas. 2. Liquid. 3. Granular Powder or Tablet
Which form of chlorine provides 100% available chlorine?
Gas
When the chlorine demand is met, the additional amount of chlorine added in anticipation of the substances yet to enter the water is called ___________.
Residual Chlorine
Free residual chlorine is in the form of hypochlorite ions and _______.
Hypochlorous Acid
The free chlorine residual must be maintained between _____ and ____ ppm.
1.0 and 4.0 ppm
The free bromine residual must be maintained between _____ and _____ ppm.
2.0 and 8.0 ppm
The process of increasing the chlorine residual to a point where all of the ammonia combined with chlorine is oxidized is called ___________ chlorination.
Breakpoint
Chlorine tablets may be placed in surface skimmers or scum gutters, T or F.
F
Indoor pools must maintain a temperature between ____ and ____ degrees F.
76 and 92 degrees F
A 40,000 gallon pool needs to be superchlorinated to 10 ppm. The chlorine residual was last measured to be 0.5 ppm. How many ounces of calcium hypochlorite (65% available chlorine) must be added? ______ ounces.
40,000 / 7,500 = 5.33 ounces. 10 - 0.5 = 9.5. 9.5 x 5.33 = 50.67 ounces. 50.67 / 0.65 = 77.9 ounces. 77.9 ounces of Calcium Hypochlorite
