The Nuts & Bolts of Pool Water Chemistry

1. The Nuts & Bolts of Pool Water Chemistry Herb Jarrell, PhD, DABCC

2. OBJECTIVE for Today To impress you with the value of being conversant with chemical names, behavior and concepts so that you will be motivated to pay attention in your fall chemistry classes by: 1) Sharing my unraveling of a mystery called Pool Chemistry 2) Giving my ULTIMATE OVERVIEW of Pool Chemistry 3) Using 1) and 2) to assess LeTourneau University’s pool.

3. Disclaimer! • WARNING! Attendance to this science seminar may destroy your comfort and security while participating in water-based recreation. • LeTourneau University can not be held liable or responsible for any changes in, or damages to, brain chemistry resulting from attendance to this seminar.

4. Biggest Problem: Obfuscations in the Pool Chemistry Industry • no indication of chemical ingredients listed on packaging • often only pool industry jargon is used on packaging • no indication of purity when there are ingredient lists • no identities of inert ingredients when their amounts are listed Note: these tend to occur because listing actual ingredients requires the use of their actual chemical names and/or formulas

5. In actuality, this talk is about:Unraveling the Maze of Pool Water Chemistry—What’s an educated person to do!? Herb Jarrell, PhD, DABCC

6. Unraveling the Maze of Pool Chemistry • I—Sorting out the Industry Jargon for Pool Chemicals • II—Anticipating the Effects of Common Pool Chemicals on pH • III—Balancing the need for “chlorine stabilizer” with optimum levels of the “chlorine sanitizer” itself • IV—Balancing the use of calcium salts with optimum levels of the calcium ion itself

7. I—Sorting out the Industry Jargon for Common Pool “Chorines” “unstabilized” chlorines = not a source of cyanuric acid • “liquid shock” = 6 or 12 % sodium hypochlorite solutions • “dry shock” = Ca (Mg or Li) hypochlorite granules “stabilized” chlorines = chlorinated cyanuric acids (CA) • CA dissolved with one of the “shocks” above • slow-“acting” = “trichlor” = symclosene • fast- “acting”: 1) “dichlor” = dichloro-CA “shock” 2) “monochlor” = monochloro-CA “shock” Note: every form of chlorine except “bleach” is “dry chlorine”

8. II—Another Problem: The 4-Fold Mantra of Pool Chemical Suppliers 1  2  3  4 balance sanitize shock algaecide pH disinfect destroy kill algae pH stabilizers water undesirable sanitizer stabilizer solutes

9. II—Anticipating the Effects of Common Pool Solutes on pH Typical Acids and Bases pKA pKCB • monoperoxysulfate-HOSO4−2 <2.0 >12.0 • hydrogen sulfate-HSO4− 2.0 12.0 • [cyanic acid-CNOH 3.46 10.54] • “carbonic acid”-CO2(aq) 6.35 7.65 • cyanuric acid-(CNOH)3 7.20 6.80 • hypochlorous acid-ClOH7.40 6.60 • ammonium-NH4+ 9.25 4.75 • hydrogen carbonate-HCO3− 10.33 3.67 • hydrogen tetraborate-HB4O7− >14 <0

10. II—Bottom Line: anticipate a chemical’s effect on pH in order to avoid generating excess salts! • Neutralizing acidity produces salt. • Neutralizing basicity also produces salt. • Eventually, you may have to drain your pool to get rid of all the discomfort of salts—burning and dry skin!

11. III—Balancing the “chlorine stabilizer” with “chlorine” itself: Chlorine Chemistry Disinfecting as simply as this chemist could conceptualize it: • Na + + ClO− + H―OH   ClO―H* + Na+ + OH− bleach* + water hypochlorous acid + sodium hydroxide • Why are the sodium compounds the only ionized chemicals? • How would you ensure that [ClO−] = [ClOH]? Typical disinfecting in the real world: • (CClNO)3 + 3H―OH  3Cl―OH + (CNOH)3 symclosene + water bleach* + cyanuric acid *Note: bleach is the actual “sanitizer” in almost all pools!

12. Check out the molecular models— they represent the four molecules which, all in equilibrium with each other, provide “stabilized chlorine”: symclosene  ClOH + dichloro-CA dichloro-CA   ClOH + monochloro-CA monochloro-CA   ClOH + cyanuric acid

13. Note about “stabilized chlorine” • The life of the “chlorine” is not being extended by being bound to the cyanuric acid molecule. • Rather, the life of the “chlorine” is being extended by the cyanuric acid absorbing UV radiation in lieu of the bleach—which would otherwise be decomposed! Question: what is the obvious remedy for having to stabilize your “chlorine”?

14. My ULTIMATE OVERVIEW of Pool Chemistry • #1 objective: providing a safe and attractive swimming environment • #2 objective: preserving your investment in your pool and in your pool equipment

15. Providing a Good Environment and Preserving the Life of your Pool—I • A. Exclusion of water contaminants • B. Ensuring good quality of water • C. Effective filtration system • D. Effective pool “vacuuming”

16. A. Exclusion of water contaminantsfrom nonhuman sources • forest litter • lawn clippings • runoff water • blowing dust & debris • algal and bacterial growth Remedies: -adequate filtering systems -and __________?

17. A. Exclusion of water contaminants from human sources • sweat & mucus • feces & urine • body lotions leached • skin sloughed • unwashed swimwear • excessive pool chemicals Remedies: • easily accessible toilets & showers • use of clean swimwear, etc. • good pool chemistry

18. B. Ensuring good quality of water geological contaminants • heavy metals • carbonates • salt industrial contaminants • groundwater access to soil contaminants • fertilizer runoff into water sources • saltwater contamination from oil/gas production

19. C. Effective filtration system • appropriate filtration pore sizes • adequate volume of filtration medium • adequate (pump) flow

20. D. Effective pool “vacuuming” • adequate scrubbing (tactile surface contact) • absence of sequestered pockets of stagnation (“cesspools”)

21. Providing a Good Environment and Preserving the Life of your Pool—II • A. Maintaining a pH of 7.4-7.6 (~ the pH of tears) • B. Maintaining a bleach concentration of 2-3 ppm • C. Destroying xppm chloramines with 10xppm of oxidants • D. Optimizing concentrations of Ca+2 and other solutes

22. A. Maintaining a pH of 7.4-7.6 This is high enough to: And also low enough to: • prevent burning of mucus membranes • prevent degradation of pool and/or pool equipment • optimize the effectiveness of the bleach • prevent burning of mucus membranes • prevent precipitation of insoluble salts on pool fixtures (“scale”) and pool liners (“stains”) • optimize the effectiveness of the bleach

23. B. Maintaining a bleach concentration of 1-3 ppm This is high enough to: And also low enough to: • inhibit microbial growth of algae and bacteria • sequester organic substances from human and nonhuman sources in a readily excuded form: chloramines • prevent burning of mucus membranes

24. Pool-borne Pathogens athlete‘s foot (fungal) ear infections (bacterial and fungal gastroenteritis (bacterial, fungal and parasitic) Legionnaire’s disease (bacterial)

25. C. Destroying x ppm chloramines with 10x ppm oxidants This is high enough to: But is also so high that it: • destroy chloramines * *Provided that A, B and D are being accomplished, all the odor and burning sensations experienced in pools are due to the presence of chloramines! • prohibits use of the pool during the chloramine exclusion process!

26. Chloramine Chemistry • monochloramines = strong odors and burning! (R)2N―H + Cl―OH  (R)2N―Cl** + H―OH • dichloramines = stronger odors and more burning! RNH2 + 2ClOH   RNCl2** + 2HOH • “trichloramine” = the strongest odor and most burning! NH3 + 3ClOH    NCl3** + 3HOH ammonia* + bleach nitrogen trichloride *usual sources: urine,sweat, microbial decomposition of proteins **Note: none of the chlorine atoms has undergone reduction yet!

27. Pool Chloramine Oxidants 1) Most common type: hypochlorite Disadvantages • at least an overnight delay in the use of the pool • If not enough is added to completely oxidize the amines, the chloramines may increase without being destroyed! • If cyanuric acid is already too high and too much “chlorine” is added (especially if it is the dichlor or monochlor form!), the “free chlorine” may remain too high to swim in—indefinitely! 2) Other types: non-disinfecting (-“sanitizing”)oxidants • Only disadvantage: currently a bit more expensive • But the one I use (monoperoxysulfate) allows reentry into the pool after only 15 minutes!

28. The Nexus of “Stabilized Chlorine” with Chloramine Chemistry • Stabilized chlorine fits the structure of a monochloramine(!): (R)2N―Cl • monochloramines = strong odors and burning! (C2H2N2O2)(CO)N―Cl + H―OH  (C2H2N2O2)(CO)N―H + Cl―OH Question: how would you eliminate this primary source of monochloramines?

29. D. Optimizing concentrations of Ca+2and other solutes • A. Minimize contact between pool surfaces and concentrated forms of pool chemicals • Soluble chemicals—predissolve* each chemical, then broadcast away from pool sides in proportion to the depth of water and allow each to diffuse before circulating water . Note: when would it be best to add a soluble chemical directly into the pumping system? *Note: make sure it is okay to predissolve the chemical! • Insoluble chemicals—place in skimmer basket or in a leg of panty hose suspended from side of pool where water enters. Note: when would it be best to add an insoluble chemical directly into the pumping system?

30. D. Optimizing concentrations of Ca+2 and other solutes • B. Maintain the optimum calcium ion concentration for the type of pool • C. Minimize osmotic strength of solutes below that of your body to prevent irritation of mucus membranes and drying or wrinkling of skin—balance additions of chemicals with additions of fresh water! How can you do this without the pool overflowing?

31. Providing a Good Environment and Preserving the Life of your Pool—III: Prerequisite Definitions • pH = − log [H+] and ppm = parts per million by mass • Thus ppm = x parts of solute/million parts solution • For example: in 1,000,000 mg of water at pH 7.4, there are 1,000 g (1 L) of water and [10 − 7.4] (0.040 mg) of H+. • For the range 7.4-7.6, the H+ is only 0.040-0.025 ppm!

32. We are now faced with a dilemma! How can such a small range of H+ concentration (0.025-0.040 ppm) be maintained when it is only about 2% of that required for bleach (1-3 ppm) to “sanitize” the pool and only about 0.1 % of that required for bleach (up to 30 ppm) to destroy chloramines? Answer?

33. Add an Effective Buffer! But… which one(s)… and how much?

34. Prerequisite Chemical Principles: Concepts of Acid-Base Equilibria • For any HB  H+ + B− , • pH = pKA − log([HB]/[B−]) • Buffering occurs most effectively when [HB] = [B−], • but [HB] = [B−] only when pKA = pH or pKCB = pOH.

35. Common Pool Chemicals Potential Buffer Solutes? pKA pKCB • monoperoxysulfate-HOSO4−2 <2.0 >12.0 • hydrogen sulfate-HSO4− 2.0 12.0 • cyanuric acid-(CNOH)3 7.20 6.80 • hypochlorous acid-ClOH 7.40 6.60 • ammonium-NH4+ 9.25 4.75 • hydrogen carbonate-HCO3− 10.33 3.67 • calcium-Ca+2 12.6 1.4 • hydrogen tetraborate-HB4O7− >14 <0 • sodium-Na+ 14.8 −0.8

36. How is our LeTourneau pool doing? THE ASSOC. OF POOL & SPA PROFESSIONALS LETU POOL Suggested Chemical Standards for Swimming Pools8-19-098-25-09 • pH 7.4 – 7.6 7.5 7.5 • “free chlorine” (available ClOH) 1.0 – 3.0 ppm 3.4 3.8 • combined (chloramine) sanitizer 0.0 – 0.2 ppm 0.3 0.4 • cyanuric acid (stabilizer) 30 – 50 ppm 5 5 • “total alkalinity” (amt of buffers) 80 – 120 ppm 59 69 • calcium hardness 200 – 400 ppm 140 130 • total dissolved solutes not to exceed 1500 ppm ---- ---- over that of pool water

37. Finally—Some Tips onPool Water Analysis—I 1) Colored pad dip sticks—32, 29 and 7 cents apiece, respectively • Insta-TEST (at Swimming Pool SuperStores): pH unusable! good “free chlorine” and total “chlorine” good cyanurates, “total alkalinity” and total hardness • Aqua-Chem 6 (at Lowe’s and K-Mart): an Insta-TEST lookalike! • hth (at WallyWorld): spuriously high pH! only free ClOH, but bleaches out! good cyanurates, “total alkalinity”, total hardness

38. Finally—Some Tips onPool Water Analysis—II 2) Wet chemical kits—cheap! • hth (at WallyWorld): good, but only total chlorine and pH • Aqua-Chem (at Lowe’s and K-Mart): equivalent to hth 3) LaMotte analyzer printouts—*no cost at S. Pool SuperStores! *acceptably accurate and precise values for all 6 basic tests plus copper, iron, nitrates, phosphates and total dissolved solids, if needed

39. THE END May you have many happy returns to your favorite swimming pool, spa, swimming hole or beach. Study hard! Dr. J.