The Nuts

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The Nuts Bolts of Pool Water Chemistry

• Herb Jarrell, PhD, DABCC

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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
  Universitys pool.

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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.

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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

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In actuality, this talk is aboutUnraveling the
Maze of Pool Water ChemistryWhats an educated
person to do!?

• Herb Jarrell, PhD, DABCC

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Unraveling the Maze of Pool Chemistry

• ISorting out the Industry Jargon for Pool
  Chemicals
• IIAnticipating the Effects of Common Pool
  Chemicals on pH
• IIIBalancing the need for chlorine stabilizer
  with optimum levels of the chlorine sanitizer
  itself
• IVBalancing the use of calcium salts with
  optimum levels of the calcium ion itself

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ISorting 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

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IIAnother 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

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IIAnticipating the Effects of Common Pool
Solutes on pH

• Typical Acids and Bases

• pKA pKCB

• monoperoxysulfate-HOSO4-2 lt2.0 gt12.0
• 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-ClOH 7.40 6.60
• ammonium-NH4 9.25 4.75
• hydrogen carbonate-HCO3- 10.33 3.67
• hydrogen tetraborate-HB4O7- gt14 lt0

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IIBottom Line anticipate a chemicals 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 saltsburning
  and dry skin!

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IIIBalancing 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!

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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

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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 bleachwhich would
  otherwise be decomposed!
• Question what is the obvious remedy for having
  to stabilize your chlorine?

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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

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Providing a Good Environment and Preserving the
Life of your PoolI

• A. Exclusion of water contaminants
• B. Ensuring good quality of water
• C. Effective filtration system
• D. Effective pool vacuuming

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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
__________?
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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

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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

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C. Effective filtration system

• appropriate filtration pore sizes
• adequate volume of filtration medium
• adequate (pump) flow

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D. Effective pool vacuuming

• adequate scrubbing (tactile surface contact)
• absence of sequestered pockets of stagnation
  (cesspools)

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Providing a Good Environment and Preserving the
Life of your PoolII

• A. Maintaining a pH of 7.4-7.6 ( the pH of
  tears)
• B. Maintaining a bleach concentration of 2-3 ppm
  
• C. Destroying x ppm chloramines with 10x ppm of
  oxidants
• D. Optimizing concentrations of Ca2 and other
  solutes

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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

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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

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Pool-borne Pathogens

• athletes foot (fungal)
• ear infections (bacterial and fungal
• gastroenteritis (bacterial, fungal and parasitic)
• Legionnaires disease (bacterial)

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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!

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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!

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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 inindefinitely!
• 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!

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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?

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D. Optimizing concentrations of Ca2 and other
solutes

• A. Minimize contact between pool surfaces and
  concentrated forms of pool chemicals
• Soluble chemicalspredissolve 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 chemicalsplace 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?

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D. Optimizing concentrations of Ca2 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 skinbalance
  additions of chemicals with additions of fresh
  water! How can you do this without the pool
  overflowing?

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Providing a Good Environment and Preserving the
Life of your PoolIII 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!

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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?

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Add an Effective Buffer!

• But
• which one(s)
• and how much?

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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.

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Common Pool Chemicals

• Potential Buffer Solutes?

• pKA pKCB

• monoperoxysulfate-HOSO4-2 lt2.0 gt12.0
• 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-Ca2 12.6 1.4
• hydrogen tetraborate-HB4O7- gt14 lt0
• sodium-Na 14.8 -0.8

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How is our LeTourneau pool doing?

• THE ASSOC. OF POOL SPA PROFESSIONALS LETU
  POOL
• Suggested Chemical Standards for Swimming Pools
  8-19-09 8-25-09
• 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

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FinallySome Tips onPool Water AnalysisI

• 1) Colored pad dip sticks32, 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 Lowes 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

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FinallySome Tips onPool Water AnalysisII

• 2) Wet chemical kitscheap!
• hth (at WallyWorld) good, but only total
  chlorine and pH
• Aqua-Chem (at Lowes and K-Mart) equivalent to
  hth
• 3) LaMotte analyzer printoutsno 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

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THE END

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