CHAPTER 5: THE CHEMISTRY OF CHLORINATION WATER CHEMISTRY: DISINFECTION CHAPTER 6: TYPE OF CHLORINE CHAPTER 7: PROTECTING CHLORINE FROM SUNLIGHT CHAPTER 8: CHLORINE GENERATORS, BROMINE, AND OZONE 2011 1 POOL WATER CHEMISRY Chapters 5 thru 8 Disinfection Pages 49 125 Chlorine Disinfection Oxidation Residual How it works: HOCl and OCl ph effect on HOCl and OCl Super Chlorination vs. Shocking Elemental Inorganic Organic Chapter 7 Protecting Chlorine from Sunlight, Bromine and Ozone 2011 2 Disinfection: (book definition on page 49) Killing pathogenic (disease-causing) organisms, such as bacteria, parasites, viruses and other organisms such as algae, mold, mildew and spores. It just means that we need to KILL the bad bugs in the water --------- 2011 3 1
Oxidation: The process of changing the chemical structure of contaminants so they are more readily removed from the water The conversion of the contaminants to simple gases so they will off-gas. 2011 4 What contaminates? Oxidation The dead bugs --- Man Made Stuff: Sweat Natural Creams Urine Suntan Lotions Saliva Soap Oils Mucous Deodorants All other body fluids Makeup Lipstick And all the other stuff listed on page 49 2011 5 The Residual After Chlorine kills the bugs (disinfects) After Chlorine oxidizes the contaminates from the water The Chlorine Demand will be met And a Chlorine Residual will be left in the water This is what we measure 2011 6 2
Disinfect Oxidize Residual Disinfection 15% Oxidation 85% 2011 7 The Chlorine in Water Reactions Cl 2 H 2 O HOCl HCl Chlorine (gas) + water > hypochlorous acid + hydrochloric acid It s the Hypochlorous acid that is important here: HOCl is the Killing form of Chlorine 2011 8 The Chlorine in Water Reactions A second reaction occurs with the Hypochlorous Acid: HOCl Dissociates into HOCl hydrogen ion H + ion OClẖypochlorite This whole thing is the Free Available Chlorine that we measure 2011 9 3
The Chlorine in Water Reactions HOCl H + OCl - 8.0 28 7.8 7.6 7.4 7.2 7.0 6.5 6.0 ph 38 49 60 71 79 92 % HOCl 2011 10 The chart on page 52 At a ph of 7.5 HOCl is about 55% The Chlorine in Water Reactions HOCl H + OCl - ph % HOCl %OCl 65 6.5 92.37 763 7.63 7.0 79.29 30.71 7.2 70.73 29.27 7.4 60.39 39.61 7.5 54.77 45.23 7.6 49.03 50.97 7.8 37.77 62.23 8.0 27.69 72.31 8.2 19.46 80.54 2011 11 Lets Look at the Residual a bit closer (HOCl H + + OCl - ) TAC Total Available Chlorine minus FAC Free Available Chlorine equals CC Combined Chlorine Recommended Chlorine levels on page 56 Chlorine that is combined with ammonia or organic material in the water Chloramines 2011 12 4
The Best way to rid the Combined Chlorine (Chloramines) Add more chlorine to the pool Equal to 10 times the measured amount of Combined Chlorine For example: If you measured.5 ppm of Combined Chlorine Simply add 5 ppm of Chlorine 2011 13 Elemental Cl 2 Inorganic -- is a Gas We Classify 3 types: Sodium Hypochlorite -- a liquid (Bleach) Calcium Hypochlorite -- a solid Lithium Hypochlorite -- a solid Organic DiChlor -- a solid TriChlor -- a solid 2011 14 Chlorine Gas ( Cl 2 ) Elemental Chlorine An element of nature Number 17 Group 17 on The Periodical Chart of the Elements Greenish yellow gas 2.5 time heavier than air Never found uncombined in nature It is dangerous An irritant at only 3ppm in air 2011 15 5
Inorganic Chlorine Liquid Chlorine Sodium Hypochlorite ( NaOCl ) One Gallon of 12 % Trade Grade contain 1 pound of Cl 2 It will degrade quickly (days) as the temperature rises (p.66) Must be packaged with a vented cap It will raise the ph acid needs to be added to the pool after using Getting it your eyes will cause permanent damage in 15 seconds 2011 16 Inorganic Chlorine Cal Hypo Calcium Hypochlorite ( Ca[OCl] 2 ) Granules but can be pre dissolved, then added as a liquid (p.66) A Class 3 Oxidizer will catch on fire easily Will raise ph Will raise calcium level for 10ppm Chlorine added, will raise calcium 7ppm Will explode if mixed with TriChlor 2011 17 Calcium Hypochlorite and a bit of Coca Cola 2011 18 6
Inorganic Chlorine Lithium Hypochlorite ( LiOCl ) White powder or Granules Dissolves very quickly Relatively higher cost Will raise ph Is Non Flammable and dust free 2011 19 Organic Chlorine ( Stabilized Chlorine Chlorine, by definition which contains cyanuric acid ) DiChlor ( NaCl 2 C 3 N 3 O 3 ) White Granules Fast Dissolving ph Neutral Only about 40% chlorine by weight 50% cyanuric acid, 10% sodium Will raise Cyanuric Acid level for 10ppm Chlorine added, will raise CYA 9ppm 2011 20 Organic Chlorine ( Stabilized Chlorine Chlorine, by definition which contains cyanuric acid ) TriChlor ( Cl 3 C 3 N 3 O 3 ) Tablets or Granular Very Slow Dissolving Low ph 2.8 to 3.0 Only about 45% chlorine by weight, 55% Cyanuric Acid Will raise Cyanuric Acid level for 10ppm Chlorine added, will raise CYA 6 ppm Do NOT put them in the skimmer 2011 21 7
Available Chlorine ph in 1% Solution ph Effect On Water Physical Form Elemental Inorganic Organic Sodium Calcium Lithium Cl 2 Dichlor Trichlor Hypochlorite Hypochlorite Hypochlorite 100 % 10 12 % 65, 70 or 75% 28 or 35 % 56 or 62 % 90 % 0 13 11.8 10.8 68 6.8 28 2.8 Lowers Raises Raises Raises Gas Liquid Granules Tablets Granules No change Granules Available Chlorine Content (ACC) is the relative amount of oxidizing chlorine as compared to chlorine gas as it is released into water Chlorine manufacturers are Required by the EPA to list the ingredients as well as the Available Chlorine Content Lowers Tablets Granules 2011 22 Chlorine Type Amount to Add for 1ppm Increase In a 10,000 Gallon Pool Gas 1.3oz. 1 pound Equivalents Liquid 12% 10.6 fl. oz. 1 gallon TriChlor 1.5 oz. 1.1 pounds About 2 tabs DiChlor 56% 2.38 oz. 1.8 pounds About.5 of 1 lb. DE Scoop Cal Hypo 65% 2.0 oz. 1.5 pounds About.5 of 1 lb. DE Scoop Lithium 35% 3.8 oz. 2.8 pounds 2011 23 So How Much Chlorine to I add? Given: A 20,000 gallon pool Put in 6ppm using Liquid Chlorine 12% Step 1: Write in the PPM increase you want to add to the pool 6 ppm Step 2: Divide the gallons in the pool by 10,000 20,000 / 10,000 = 2 Step 3: Use Table 6 2 on page 91 Find the Chlorine Type Add write in the 1ppm amount 10.6 fl. oz. Step 4: Multiply Box 1 X Box 2 X Box 3 127.2 fl. oz. Divide by 128 to convert to gallons 127.2 / 128 = about 1 gallon 2011 24 8
Protecting Chlorine from Sunlight Chapter 7 Pages 95 104 The Sun s Ultra Violet (UV) rays degrades the chlorine in swimming pools But we can protect tthe chlorine by using the Chemical Cyanuric Acid (CYA) It is sold as: Chlorine Stabilizer Pool Water Conditioner 2011 25 Protecting Chlorine from Sunlight Chapter 7 Pages 95 104 There is a controversy in our industry over Cyanuric Acid (CYA) It centers around two facts: 1. Cyanuric Acid DOES protect chlorine from the Sun But HOW MUCH does it protect and HOW MUCH is needed is the debate. 2. Cyanuric Acid DOES slow down the kill time of Free Chlorine But HOW MUCH does it slow the kill time of Free Chlorine is the debate. 2011 26 Protecting Chlorine from Sunlight Chapter 7 Pages 95 104 Fortunately we do have a few guidelines You should only use about 10 times (ppm) of CYA For every 1 ppm of Free Chlorine you want to protect The APSP Recommendations: Minimum Ideal Maximum Cyanuric Acid 10 ppm 30 50 ppm 100 ppm 2011 27 9
Protecting Chlorine from Sunlight Chapter 7 Pages 95 104 CYA is good but only when used within the Recommended Guidelines Without CYA the intense summer time sunlight will degrade chlorine 90 95% 95% in just 2 hours CYA will hold the Free Chlorine in the water 6 to 10 times longer (p95) or 4 to 8 times longer (p96) depending on what you read 2011 28 Protecting Chlorine from Sunlight Chapter 7 Pages 95 104 Adding more CYA than the recommended Guidelines will NOT protect it any more from the sun Its just a waste of money AND It will continue to slow down the kill time of Chlorine CYA will not LOCK UP chlorine (that s a myth) 2011 29 Protecting Chlorine from Sunlight Chapter 7 Pages 95 104 A couple of other notes about Cyanuric Acid You can always add more But the only practical way to lower it is by Diluting or Drain/Refill Bromine is NOT protected by Cyanuric Acid 2011 30 10
Protecting Chlorine from Sunlight Chapter 7 Pages 95 104 Cyanuric Acid C 3 N 3 O 3 Cyanuric Acid C 3 N 3 O 3 Cl 3 With 3 chlorines Attached to the Nitrogen is TriChlor 2011 31 Chlorine can be produced by passing a electrical current through water that has salt in it. Three things are produced: 1. Hydrogen gas ( H 2 ) at the negative electrode 2. Sodium hydroxide ( caustic soda ) at the positive electrode 3. Chlorine gas ( Cl 2 ) also at the positive electrode 2011 32 There are two types of : 1. In Line salt directly in the pool 2. Brine salt in a separate tank 2011 33 11
Chlorine Generation the In line system 3 4 1. Add the salt ( adding Cl ) 2. Pass the salt water ( Cl ) through an electrical current This changes Cl to Cl 2 3. Cl 2 dissolves to make HOCl 2 1 4. HOCl disinfects and oxidizes Reducing it to Cl 2011 34 Chlorine Generation the Brine System With the brine system this re cycling does not happen There are two cambers in the tank: a positive charged camber the anode and a negative charged camber the cathode Cl 2 ( Chlorine Gas ) is produced in the anode (Positive) camber. Chlorine Gas is then injected into the water With the brine system you must replenish the salt in the anode camber. 2011 35 Chlorine Generation Most residential chlorine generators produce about 1 pound of Cl 2 (pure chlorine) per 24 hours How much salt is needed? Most systems require about 3000 to 3500ppm One pound of salt in a 10,000 gallon pool is about 12ppm 2011 36 12
Bromine Bromine is an Element just like Chlorine But it s a liquid not a gas It s in the Periodic Table Number 35 In the Halogen Group (Group 17) 2011 37 Bromine Br 2 H 2 O HOBr HBr Bromine + water > hypobromous acid + hydrobromic acid It s the Hypobromous acid that is important here: HOBr is the Killing form of Bromine 2011 38 Bromine The Elemental Liquid is not used in swimming pools Two types of bromine compounds are used: 1. Two part bromine 2. Bromine Tablets 2011 39 13
Bromine Like Chlorine once it has done its job it is reduced to negative ions Br But unlike Chlorine Bromine can be recycled or reactivated by adding an oxidizer: Chlorine or Potassium Monopersulphate 2011 40 Bromine HOBr H + OBr - The chart on page 177 At a ph of 7.5 HOBr is about 94% ph % HOBr %OBr 6.5 99.4.6 7.0 98.0 2.0 7.5 94.0 6.0 8.0 83.0 17 8.5 61 39 2011 41 Bromine Like Chlorine Is destroyed/degraded by the sun s UV rays It will degrade at a lesser rate than Chlorine: About 65% in 2 hours. (Chlorine degrades about 90 95% in 2 hours) Unlike Chlorine Bromine is not protected from the sun with Cyanuric Acid 2011 42 14
Ozone (O 3 ) It is a Gas It is a great Disinfectant and Oxidizer It is 25 times faster at killing than Chlorine (HOCl) There are two methods of making Ozone: 1: UV 2: Corona Discharge 2011 43 Ozone (O 3 ) Ozone must be dissolved in the water to work It is usually injected into the return plumbing after all the equipment via a Venturi system 2011 44 Ozone (O 3 ) Even though Ozone is a great disinfectant and oxidizer there is little to no residual Consequently A Chlorine residual must be maintained AND CERTIANLY NO Un dissolved should ever enter the pool 2011 45 15
Any Questions? 2011 46 16