INTERMEDIATE POOL & SPA WATER TESTING

by: Andrew Roberts. Industrial Test Systems, Inc.

WELCOME!

IN THIS SEMINAR:

Touching on the basics:•Sanitizers

•pH

•Total Alkalinity

•Temperature

•Calcium Hardness

•Total Disolved Solids

IN THIS SEMINAR:Going a Step Beyond:• Metals

• pH / Total Alkalinity Testing & Adjusting

• Effects of Cyanuric Acid on Total Alkalinity Results

• Langelier’s Saturation index

• Hamilton’s Index

• Corrosion & Flowrate

• Hot Water Chemistry

IN THIS SEMINAR:

Finishing with best testing practices and methods

:)

BASIC MAINTAINANCE & UPKEEP:

• Protect swimmers and bathers [desease & infection]

• Protect pool surfaces and equipment [corrosive & scaling water]

• Produce aesthetically pleaseing water [pool looks good]

OTHER IMPORTANT FACTORS INCLUDE:

• Water circulation

• Filtration

• Physical maintenance practices

A QUICK OVERVIEW OF THE BASICS:

• Sanitizers / Sanitizing

• pH

• Total Alkalinity

• Temperature

• Calcium Hardness

• Total Dissolved Solids [TDS]

SANITIZERS / SANITIZING:

• Most Popular:

• Chlorine

• Bromine

• Copper Ionization

• Salt Systems

• Reduce pathogenic organisms to acceptable levels.

• Protect bathers from disease and infection.

• Good sanitation = sanitizer residual is maintained at all times.

• Sanitizer levels should be regularly monitored using an accurate test kit.

PH:

•Influences effectiveness of sanitizers and oxidizers.

•Best ranges for pH = 7.4 - 7.6 ( 7.2 -7.8)

•affects swimmer comfort.

•Above 7.8, Sanitizer less effective at killing bacteria and algae.

•Below 7.2, pH becomes acidic, especially when combined with low TA.

•raise pH, add Sodium Carbonate [soda ash]. NOT the same as Sodium Bicarbonate [baking soda]

•To lower pH, add Acid [Muriatic]

TOTAL ALKALINITY:• The 'buffering capacity' if water. [Ability to resist rapid changes in pH]

•Good TA allows for easy adjustment of pH.

•Adjust TA before adjusting pH.

• Recommended levels = 80-120ppm - depending on type of sanitizer

• Low TA can lead to 'pH Bounce',

• Increase TA by adding Sodium Bicarbonate [baking soda].

•Decrease TA by adding Acid [pH will need to adjusting after].

TEMPERATURE:

• Typical pool temperature = 78 - 82 F

• Typical Spa temperature = no more than 104 F

•High temperatures can lead to calcium becoming less soluble [forming calcium carbonates].

•Gasses become less soluble, causing evaporation or 'Gas Off'.

• Evaporation leads to Carbon Dioxide leaving the water, resulting in a raise in pH.

CALCIUM HARDNESS•Calcium Ions [Ca+2], expressed as calcium carbonate [CACO3]

• Low calcium [soft water], = water dissolving calcium from other areas (pool liners, etc.) causing pitting, corroding.

•High calcium [hard water, supersaturated], = cloudy water, calcium deposits

• Typical calcium hardness levels in pools = 150 - 1,000ppm [as CaCO3]

• Typical calcium hardness levels in spas = 150 - 800ppm [as Caco3]

• Ideal range in both pools and spas = 200 - 400ppm [as CaCO3]

TDS:• The measure of all dissolved matter in water

• Increase of TDS = accumulation of impurities during course of operation.

•High TDS = hazy water, corrosion of fixtures, inhibits sanitation.

• To lower TDS, drain and fill with water that has a lower TDS than the pool water.

• TDS should never go above 1,500ppm greater than the startup TDS

• Startup TDS = Fill water + salt, start up chemicals, etc.

• The lower the TDS, the better

GOING A LITTLE FURTHER

• Metals

• pH/TA measuring & adjusting

• Effects of CYA on TA test results

• LSI [Langelier Saturation Index]

• Corrosion & Flowrate

• Hamilton Index

• Hot Water Chemistry

METALS:• Dissolved metals are present in all common water sources

• Concentrations can vary widely from regions, to communities.

• Metals cause staining on pool surfaces.

• Colors of pool water from metal concentrations:

•Brown

•Blue

•Green

•Grey

•Black

METALS AND THEIR COLOURS:

Manganese: Black-Brown-Purple cast [typically not noticed until addition of Chlorine or pH is raised]

Copper: Light blue or green cast [when dissolved / in solution].

Turquoise or black [when oxidized / precipitated].

*Causes hair to turn green in some cases*

Iron: Clear green / cloudy yellow to rust brown [when oxidized / precipitated]

*typically found in water taken from wells or rivers*

METAL LEVELS / REMOVAL:

Metals under 1.00ppm:

• Typically stay in solution [not yet precipitated / oxidized]

• removed by chelating or sequestering agent combined with a filter, or proprietary polymers

Metals over 1.00ppm:

• Typically precipitate / fall out of solution.

• removed by adding sequestering agent combined with a filter, or proprietary polymers

PH & TOTAL ALKALINITY MEASURING & ADJUSTING:

Typical kits use: bromocresol green-methyl red as end point indicator.

[Green - red colour development]

*Interference with CYA*

Other indicators: methyl orange

[Yellow - orange colour development,

Chlorine can bleach indicator]

*Interference with CYA*

eXact method uses: Alizarin Red S + Citrate

[yellow - orange colour development]

*NO Interference with CYA*

EFFECT OF CYANURIC ACID ON THE TA TEST:

CYA in water can contribute to certain test kits’ TA readings. [Higher readings]

CYA is a weak buffering agent.

Happens when TriChlor or DiChlor is used as sanitizer.

When calculating LSI, the true carbonate alkalinity is used. [must calculate CYA percentage contributing the TA reading 1st].

The percentage of CYA adjustment varies with pH. [pH test are typically done when calculating CYA effect on TA]

*Typically a factor of 33% (0.33) is used*

CYANURIC CORRECTION FACTOR:

• *Typically a factor of 33% (0.33) is used*

pH FACTOR

7.0 0.23

7.2 0.27

7.4 0.31

7.6 0.33

7.8 0.35

8.0 0.36

HOW TO CORRECT TA READINGS:

2 step method is used (when CYA is present)

1. Measure TA and CYA

2. multiply CYA by factor adjustment

3. Subtract factored CYA result from TA result.

TOTAL ALKALINITY EXAMPLE

Example:

1. TA = 120ppm CYA = 40ppm [pH = 7.6]

2. 40ppm x 0.33 = 13.2ppm

3. 120 - 13.2 = 106.8ppm

TRUE carbonate alkalinity = 106.8ppm

Saturation Index (SI) = A value that indicates if a Pool / Spa is balanced or not.

To calculate SI, measure:

● pH ● *Temperature ● *Calcium Hardness● *Total Alkalinity● **TDS

*pH is the only parameter that does not have a conversion factor.

**TDS is the only parameter that has a conversion factor but does not have a conversion table.

LANGELIERS SATURATION INDEX:

LSI CONVERSION FACTORS

TDS in ppm Factor Used

0 - 1000 12.1

1000 - 2000 12.2

2000+ 12.3

TDS FACTORS FOR LSI:

LANGLIER SATURATION INDEX (LSI):

•SI = pH + TF + CF + AF - 12.1*

• Acceptable SI value = -0.3 to +0.5

• Ideal SI value = 0.0 to +0.5

• Balanced water = 0.0

• *Please note: even though SI might = -0.3 to +0.5, balance might be difficult to maintain if one or more of these parameters are outside of the recommended concentration range.*

• The following slide is an example of this

LSI EXAMPLE:

•pH = 7.0

•Temperature = 84F

•Calcium Hardness = 75ppm

•Total Alkalinity = 1,100ppm

•TDS = 750ppm

•SI = 7.0 +0.7 + 3.0 1.5 - 12.1

•SI = 0.0

LSI EXAMPLE:

•Although SI says the water is balanced:

• Low pH & Calcium Hardness = Corrosive water

• High Total Alkalinity = Over buffered pH (difficult to edit pH)

CORROSION & FLOW RATE:

Many factors contribute to corrosion on wetted surfaces, these include (not are not limited to):

• aggressive water [low pH, TA and calciumhardness]• high halogen levels [Cl and Br]• dissolved gasses [especially with well water]• high mineral content [TDS, leads to high electricalconductivity]• high water temperature• high flow velocities• turbulent flow• galvanic corrosion [when 2 dissimilar metalsare in contact]

HAMILTON INDEX

● Who: Jacques Hamilton [CA pool tech]● What: 3 Step procedure to achieve water balance

• When: early 70’s

• Why: Stick it to Langelier [LSI developed for municipal water, edited by P&S adapters so much that it didn’t work any more - Hamiltons 2 cents]

HAMILTON INDEX:

3 Step Approach:

1: Test TOTAL HARDNESS [NOT Calcium Hardness] and derive Total Alkalinity level from chart

2: Adjust Total Alkalinity as indicated on chart

3: Adjust & maintain pH levels between 7.8 - 8.2

HAMILTON INDEX CHART:

HOT WATER CHEMISTRY & WATER BALANCE IN SPAS:

pH & TA:

Difficult to control due to:

● High temperature [rapid loss of CO2]

● Aeration [jets and air blowers]

● Higher bather load [more bather:water volume ratio]

HOT WATER CHEMISTRY & WATER BALANCE IN SPAS

Typically:

● pH raises [CO2 leaving Pool]

● Acid only lowers pH temporarily

● Too much acid = loss of buffering capacity [LOW TA]

pH to drop too low too quickly

very difficult to get pH in control

WHY PH INCREASES IN SPAS:

2 factors:

1: dissolved gasses become less soluble as temp increases

2: Carbon Dioxide [CO2] as Carbonic Acid [H2CO3] = lower pH.

*HOWEVER high temps & air jets= CO2 leaving water.*

[This = reduced acid concentration, thus raising pH]

Without Carbonic Acid, bicarbonates can not can not control pH raising. [typically raising to 8.2-8.4pH]

WHY PH INCREASES IN SPAS:

•High pH & Temp = bicarbonates to convert to carbonates [loss of CO2 & H20]

•The result [CaCO3] =

● Scaling● Cloudy Water● Clogged Heaters● Rough Spa Surface

• Discolored Spa Service

•NOTE: pH will change, TA will not

BATHER LOAD AND PH IN SPAS:

High bather load = lowering of pH [usually]

why: perspiration & other slightly acidic materials

Where: not so much in residential [lower bather load]

more so in commercial [higher bather load] = consistently low pH,

pH increasers needed

PH & SANITIZERS IN SPAS:

•Low pH sanitizers can decrease spa water pH.

•Low pH Sanitizers:

● TriChlor tabs = 2.9pH● Bromine tabs = 4.0pH

• Non-Chlorine MPS shock = low pH [not defined]

PH & SANITIZERS IN SPAS:

•High pH sanitizers can increase spa water pH.

•High pH Sanitizers:

● Lithium Hypochlorite = 10.7 pH● Cal Hypo = 10.8pH● Sodium Hypochlorite = >12pH

*less effective:Granular DiChlor = 6.0pH

•Biguanide = 5.5pH

SPA SURFACES & PH:

•Plaster surfaces typically increase pH [highly alkaline nature of plaster]

•Redwood hot tubs typically decrease pH [by adding acidic materials]

TA BUFFERING AGENTS USING PHOSPHATES [H2PO4-/HPO4-]:

•Phosphate buffers can be useful [depending on application]

● PROS:

• Loss of CO2 does not affect Phosphate buffers

• Phosphate buffers lower @ 7.2 - 7.5pH

• Bicarbonate buffers higher @ 7.8 - 8.2pH

TA BUFFERING AGENTS USING PHOSPHATES [H2PO4-/HPO4-]:

● CONS:

• Phosphates + Calcium = Calcium phosphate [cloudy water]

• If fill water is high in Ca, Ca increase is used = Cloudy water

• Adding Phosphates decreases Ca levels

• Ca increaser can not be added [cloudy water if added]

• low Ca can damage plaster pool surfaces

• Phosphates can add to algae production [mostly in outdoor pools]

WATER HARDNESS IN SPAS:

•Calcium carbonate = ‘the hard-water’ mineral

•dissolves as: Calcium ions & Carbonate ions [until water is fully saturated]

•Warmer water needs less ppm to be ‘fully saturated’

•Fully saturated = additional Calcium ions + Carbonate ions [calcium carbonate precipitate].

•*Scale is more of a problem for hot water [spas] than cold water [pools]

● SI is used to determine proper balance of Ca with:● Temperature● pH● Total Alkalinity

HOW TO RAISE CALCIUM HARDNESS (IN SPA WATER):

•Add Hydrated Calcium Chloride [77% typically]

•1 tbsp per 100 gal = 25 ppm increase in Ca

•if pH & TA are balanced, Ca = 200 - 400 ppm

TESTING & BEST PRACTICES:

• Circulate pool water

• Rinse sample vial 2-3 times with test sample

• Collect sample 18” below surface

• Do not collect sample near return lines

• Note temperature of water

• Test immediately after collecting sample

TESTING & BEST PRACTICES:

• Look out for Expiration dates on Reagents and strips

• Keep reagents tightly capped, in cool dark area

• Do not swap caps on reagents [cross contamination]

TESTING & BEST PRACTICES:

• Add reagents carefully [correct amount of drops, drops are equal and full sized]

• Mix reagents with test samples thoroughly

• Match visual tests in proper conditions:

• Proper lighting

• No sunglasses

• Use appropriate background

• Avoid bright sunlight

COMMON TESTING TOOLS:

• Photometers and Reagents

• Titration Reagents

• Comparator Test

• Test Strips

TESTING TOOL #1 PHOTOMETER AND REAGENT: (MOST ACCURATE METHOD)

•Uses photometric or precipitation chemistries - the color (or precipitate) is measured by a digital measuring instrument

•No visual color matching

•Measure transmission of light through the altered water sample

•Most accurate of all tests with 0.01PPM resolution

TESTING TOOL #1 PHOTOMETER AND REAGENT: (MOST ACCURATE METHOD)

• New technology uses smartphones / tablets for data collection [such as]:

• Date / Time stamps• Customer / location recording• Daily / weekly / Monthly reporting• Sharing of results

• Lower cost due to less hardware needed in meter

• Same easy to use technologies

TESTING TOOL #2 COLORIMETRIC (VISUAL) TITRATION:COMMONLY USED DPD METHOD

•Use visual color change for determining concentration

•End point color change can be difficult to judge

•Accurate counting of drops required

•Technique dependent (swirling but on site mixers are now available)

•Math required

•For Chlorine 0.2 PPM and for Hardness 20PPM is typical resolution

TESTING TOOL #3:COLORIMETRIC REAGENT WITH COLOR COMPARATOR

• Inexpensive reagents

• Gives only minimum resolution

• Reagents have stability issues

• Requires good visual judgment

•Gives only 0.4 resolution for pH and 1PPM resolution for Chlorine

TESTING TOOL #4TEST STRIPS WITH VISUAL MATCHING COLOR CHART

•Quick and easy

• Inexpensive

•Suitable for screening

•Good shelf life

•pH resolution of 0.4

•Poor chlorine resolution of 1 PPM or greater

USEFUL RESOURCES:

• Book: Pool Chlorination Facts by Robert W. LowryBook: Pool Chlorination Facts by Robert W. Lowry

• Book: Intermediate Training Manual Part 1-Book: Intermediate Training Manual Part 1-Chemicals by Robert W. LowryChemicals by Robert W. Lowry

• Book: The Ultimate Guide to Pool Maintenance by Book: The Ultimate Guide to Pool Maintenance by Terry TamminenTerry Tamminen

• Book: The Pool Maintenance Manual by Terry Book: The Pool Maintenance Manual by Terry Tamminen  Tamminen  

• New Jersey Dept of Health Checklist: New Jersey Dept of Health Checklist: http://www.state.nj.us/health/forms/ehs-13.pdfhttp://www.state.nj.us/health/forms/ehs-13.pdf

• Internet: CDC   Internet: CDC   http://www.cdc.gov/healthyswimming/http://www.cdc.gov/healthyswimming/