Salt Pools 101 and the importance of constant testing

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Salt Water Pools 101Salt Water Pools 101(And why strive for Accurate Test Results)

By Ivars Jaunakais

Friday, February 22, 2014 10:00 a.m. 2 CE hours

• History and benefits of salt pools• Importance of balanced water• Different and proper water testing methods and

techniques• What tests are needed for salt pools• Q & A

TODAY’S TOPICS

HISTORY OF THESALT POOL

• Developed in Australia - 1965• 80% of all Australian pools use salt

• Introduced in USA - 1980• Popularity in USA caught on in the last 10 years as technology improved

HISTORY OF THESALT POOL

• In 2007 nearly 75% of American new pool installations were salt pools

• An increase of 15% from 2002• Currently over 1.6 million pools in the United States use salt

CHLORINE IS GENERATED!

• Saltwater pools generate a steady flow of chlorine

• Traditional chlorine pools buy, handle and manually add chlorine

• This steady flow keeps the chlorine level consistent, and minimizes highs and lows for chlorine

SALT WATER BENEFITS

• Salt water is gentler on skin, eyes, nose and hair

• Simple and convenient maintenance • Environmentally friendlier (no chlorine to store)

• Less expensive to operate in the long run

• Less prone to algae problems

• Adequate generation of Chlorine by Salt System

• Regular testing of water

• Cleaning and Maintenance

• Adequate circulation time

• Quality filtration

• Rain dilution of salt levels

• Know what’s in the make-up water to anticipate problems

you may be adding to the pool

• Back flushing effects?

MAINTAINING A SALT POOL

• Proper maintenance of a salt poolrequires routine testing

• Adds comfort and safety for bathers• Avoids liability issues with owner • Accurate testing keeps problems

at a minimum • Testing helps to keep salt pool balanced • Accurate Chlorine levels are needed to know if Salt

System is adjusted properly

TESTING IS VITAL

• Weekly testing of pH and chlorine

• Monthly testing for total alkalinity, calcium hardness, metals, salt, and cyanuric acid

• Testing of salt levels need to match the levels of salt specified by the chlorine generator manufacturer

TESTING IS VITAL

• Happy customers • Accurate and correct maintenance, which avoids customer complaints

• Increase business with service reputation

SERVICE GOALS

• pH levels rise due to constant electrolysis (if problem continues consider adding Borate Buffer to 50PPM)

• Regular if not weekly muriatic acid additions may be needed to keep pH OK

• Muriatic Acid lowers total alkalinity levels• Monitor Cyanuric Acid levels • Monitor Salt level• Corrosion of metal parts• Higher electricity use

SALT POOL ISSUES

•Control box settings•Pool circulation time settings•Salt and concrete•Effect of backwash on plants

ADDITIONAL ISSUES

• Poolside testing often performed in undesirable environmental conditions

• Temperature, humidity, sunlight, wind, and rain affect results

• Distractions including poolside activity and noise

POOLSIDE TESTING CHALLENGES

• Cost per test (varies $0.02 to $0.30 up to $10)• Time to run test (time equals money)• Ease of use• Portability and stability of tests• Compliance testing requirements if testing public

or commercial pools and spas (meets Florida Health Department approval)

• Test gives good results with a test Standard

TESTING CONSIDERATIONS

• Be acceptable or compliant (i.e., Chlorine test uses DPD indicator as required by Health Dept.)

• Use tests that don’t challenge your patience• Not be technically difficult• Use reagents and equipment that are safe, reliable, and stable

• Have good resolution (lower resolution gives better accuracy)

• Be accurate (accurate test results give accurate maintenance)

YOUR TESTING SHOULD…

• Colorimeters (Photometers) and reagents

• Titration or drop reagents • Comparator test• Test Strips

COMMON TESTING TOOLS

Four colorimetric methods:1) Digital Photometer – uses different reagents

(liquid, powder, tablet, or reagent strip)

2) Colorimetric titration - counting drops and matching color using liquid and powder reagents

3) Comparator color test – uses liquid, powder, tablet, or reagent strip with a test tube or comparator color chart scale

4) Test strips - visual matching to a color chart scale

COLORIMETIC TESTS

• Uses colorimetric or precipitation chemistries and the color (or precipitate) is measured by a digital instrument that measures light transmission through sample

• Concentration is determined by the amount of light that is transmitted through the reacted pool water sample

• Chlorine has 0.01 PPM resolution; 0.03 PPM accuracy• Hardness has 1 PPM resolution; 10 to 20 PPM accuracy

TESTING TOOL #1Photometer and Reagent

(Most accurate method)

RESOLUTION EFFECTS ACCURACY!

Resolution 1 ppm Resolution 0.1 ppm

• Visual color change determines concentration• End point color change must be monitored • Accurate counting of drops is required• Test is dependent on technique (swirling)• Math required (drops are multiplied by

concentration factor) • Chlorine has 0.2 PPM (or 0.5PPM) resolution

and expect 0.6 PPM (or 1.5PPM) accuracy• Hardness has 20PPM resolution; 60 PPM

accuracy

TESTING TOOL #2 Colorimetric (visual) titration

Commonly used FAS/DPD method

• Fast and inexpensive

• Liquid reagents are known to have stability issues

• Requires good visual judgment

• Chlorine has 1 PPM resolution and 3 PPM accuracy at lower levels

• pH has 0.3 resolution; 0.5 accuracy

TESTING TOOL #3 pH and Chlorine COLOR COMPARATOR

• Very Fast and inexpensive

• Ideal for Pools with no issues

• Good shelf life

• pH resolution is 0.3 and

accuracy is 0.5

• Chlorine resolution is 1 PPM

or greater and accuracy is 3 PPM

• Available for most parameters

TESTING TOOL #4 Multipad Test Strips

COLOR BLINDNESSOver 32 million Americans (8% or 1 out of 12 men) have varying degrees of color blindness

COLOR BLINDNESS

SALT WATER POOL TESTING

BEST PRACTICES

• Circulate pool water before collecting sample, or manually stir water in sample area

• Rinse sample cell/vial two or three times with pool water before sampling

• Sample water 18 inches below surface (most important for Chlorine, Bromine, and Cyanuric Acid testing)

TESTING BEST PRACTICES

• Do not collect water sample near return lines

• Note the temperature of water to be tested (cold or hot water can effect test results)

• Read test instructions for procedure how to run test with cold or hot water


• Perform tests as soon as possible after collecting sample (immediate testing is required for accurate Free Chlorine results)

• If collecting samples for later testing, handle carefully to avoid contamination, fill bottle to capacity, & seal sample bottle tightly


• Pay careful attention to expiration dates on reagents and test strips

• Keep reagent containers tightly capped and store in a cool, dark place when possible.

• Don't swap/mix the caps on reagent bottles to avoid chemical cross contamination


• Where required, measure volume of water sample to be tested (Measure the bottom of sample meniscus, not the top at fill mark)

• Don't interchange sample vials or cells

• Follow manufacturer’s test directions carefully


• Add liquid reagents carefully – make sure the correct number of drops are added to sample and drops are equal and full-sized

• Mix reagents with test samples thoroughly


Match visual test results under right conditions:

1.Proper lighting

2.Don’t wear sunglasses

3.Read colors against an appropriate background

4.Don’t match colors in bright sunlight


• Record test results and maintain records for each pool or spa

• Never dispose of tested samples/reagents in the pool

• Rinse sample test vials and cells immediately after testing


• When using a photometer, verify your results using a Pool Water Standard to verify photometer, reagents, and operator

• Pool Water Standards can also be used for verifying titration and comparator reagents


AVERAGE ACCURACY YOU CAN EXPECT

IDEAL LEVELS for Salt PoolsCHEMICAL IDEAL LEVELS

Salt 2700 to 3400 ppm

Free Chlorine 1.0 to 3.0 ppm

Cyanuric Acid 60 ppm (consider 20 to 40ppm)

Total Alkalinity

80 to 120 ppm

Calcium Hardness

200 to 400 ppm

Metals (Copper?)

0 ppm

Saturation Index

-0.2 to +0.2 (non-salt pools -0.5 to +0.5)

Nitrates at 0 PPM

BALANCED WATER• Healthy Water is Balanced Water• For balanced water 6 parameters to consider and they

are used to calculate (Langelier) Saturation Index (SI)1) pH

2) Total Alkalinity

3) Calcium Hardness

4) Total Dissolved Solids (TDS)

5) Temperature

6) Cyanuric Acid (CY)

• Balanced Water is water that will neither scale nor corrode pool or spa surfaces and/or equipment

• Corrosion is the dissolving or wearing-away of pool wall, pipes or equipment (SI value below 0.2)

• Scale is the white deposit or precipitate that builds up on fixtures, surfaces, & equipment (SI value above 0.2)

• Balanced water is non-irritating to eyes & skin of bathers, & allows sanitizer to work effectively (SI is perfect when 0 but OK between -0.2 to +0.2)

BALANCED WATER

• Protects bathers health – prevent transmission of infectious disease,

prevent skin irritation, respiratory problems, eye irritation; etc

• Protects Pool or Spa surfaces & Equipment from corrosion and/or scale-

formation, & discoloration

• Minimizes potential Health hazards from disinfection by-products

(combined chlorine is especially a problem for indoor pools/spas)

• Maintains compliance with Florida Health Dept regulations

“Majority of pool problems are caused by unbalanced water”

BALANCED WATER

• Chemicals found in make-up water, when treated by the municipal water treatment plant. Including disinfection by-products: lime, alkalis, phosphates and ammonia that forms monochloramines (combined chlorine compounds)

• Metals in make-up water is frequently found because pipes corrode as water flows through them

• Chemicals used to treat pool water - pH correction chemicals, sanitizers, oxidizers, stabilizer, chemicals for treating algae, mold, etc.

CHEMICAL SOURCES IN POOL WATER

• Bather sweat, urine, dirt, lotions, sunscreen, cosmetics, soap, deodorant, hair spray, etc.

• Environmental items - debris, dirt, leaves , vegetation, etc., contribute to problems

• Disinfection by-products - trihalomethanes, haloacetic acids, chlorate, nitrogen trichloride, etc.

• Rain water (can dilute your balanced water)

OTHER THINGS IN POOL WATER

PARAMETERS YOU SHOULD TEST

CYANURIC ACID (CY)

• Used since 1956 in outdoor pools to protect chlorine from the Sun’s ultraviolet rays (Degradation)

• CY controls stability of the chlorine in the water but increases the amount of chlorine needed to maintain proper chlorine balance in pools

• CY buffers the pH against downward changes

• Contributes to the overall Alkalinity level

CYANURIC ACID (CY) and 10x RULE

Effectiveness of chlorine protection to keep pool clean and algae free is influenced by the CY concentration RATIO to Free Chlorine concentration

• Ratio of 8 to10 times is suggested to be best for clean pools

• When the CY level is 40 PPM then keep Free Chlorine level at 4.0 PPM (10X RULE)

• So if your pool has 100 PPM CY then technically you should have 10 PPM Chlorine (10X RULE)

CYANURIC ACID (CY)• CY forms weak reversible complex with Free Chlorine• CY does not affect tests for Free Chlorine (FC)• CY/FC complex is affected by pH and concentration of

FC and CY• CY/FC Complex ties up as much as 95% of the Free

Chlorine. If your test reads 4.0 PPM FC then your complex free chlorine level is about 0.2 PPM

• As little as 0.01 to 0.05 PPM Free Chlorine is needed to keep pool clean according to CDC and World Health

CYANURIC ACID (CY)

• Effective concentration is 10 times the Free Chlorine concentration (10X RULE)

• Amount recommended to stabilize Free CL 10 ppm CY - 1.0 ppm Free CL 20 ppm CY - 2.0 ppm Free CL

30 ppm CY - 3.0 ppm Free CL 40 ppm CY - 4.0 ppm Free CL

50 ppm CY - 5.0 ppm Free CL

CYANURIC ACID (CY)• If CY is NOT used in an outdoor pool anticipate 75% Free

Chlorine degradation every 60 minutes on a sunny day • Makes good economic sense to use CY for Free Chlorine

protection – less chemicals = less money on Chlorine• Free Chlorine of 3.0 ppm in the pool then a good level of

CY is 20 to 30 ppm• NEW recommendations by CDC is to limit the CY level to

a maximum of 60 PPM • As CY increases, SI decreases so pool water becomes

more corrosive

CY AND TA• Cyanuric Acid (CY) effects Total Alkalinity (TA) in the

pool

• CY elevates TA and is influenced by the pH: CY of 40 PPM with 7.0 pH elevates TA by 8.8 ppm

CY of 40 PPM with 8.0 pH elevates TA by 14.4ppm

• So If you keep CY levels at or below 40 ppm the TA effect averages about about 10 ppm and at this point you can ignore CY influence on TA.

• One more reason to keep CY below 40 PPM

CY AND TA

• Keep CY levels at or below 40 ppm the TA effect averages about 10 ppm and so below 40 PPM CY you can mostly ignore CY influence on TA.

• This is another reason to keep CY under 40 PPM

CYANURIC ACID IN THE U.S.

One study 20 Years ago reported:• Average concentration – 76 ppm

• Maximum concentration – 406 ppm

• Recent study reported 25% (122 of 486) of private pools had more than 100 ppm

• CY is allowed for public pools in every State except New York

• CDC recommends CY levels below 60 PPM because higher levels have potential problems

MY CYANURIC ACID (CY) GUIDELINES

• Optimal level for cyanuric acid is 20 - 50 ppm• Levels above 50 ppm reduce chlorine effectiveness• Health Departments will close commercial pools

above 100 ppm (Florida level is 60 ppm)

• To reduce CY levels, partially drain pool and refill • Test and keep track of CY levels regularly if you use

Dichlor or Trichlor in your service. Salt pools eliminate this practice.

VARIATIONS IN CY LEVELS

CY levels at the bottom, mid- and surface-levels at the deep end of one Olympic-sized pool with poor water circulation were found to vary:

• Bottom – 100 ppm (12 feet)

• Mid-level – 50 ppm

• Pool surface – 20 ppm

• Photometric (1 ppm)

• Visual black dot comparator (over 20 ppm)

• Test Strip (over 50 ppm)

CYANURIC ACIDTEST METHODS (resolution)

• Use a Photometric method to get accurate test results for Cyanuric Acid

• Very important when you want to keep CY between 20 - 50 ppm

CYANURIC ACIDTESTING IN THE FUTURE

TOTAL ALKALINITY (AL)• AL is a measure of how much acid can be added to a liquid without causing a significant change in pH

• AL is the ability of water to resist a change in pH -“Buffering capacity”

• Water with AL of 80 to 120 PPM will resist wide & rapid fluctuations in pH (called pH bounce)

• AL is the bicarbonates, carbonates, & hydroxides in water

• Proper AL stabilizes pH

TOTAL ALKALINITY (AL)

• Total Alkalinity is key to pH water balance

• Recommended that it should be adjusted

FIRST, before pH

• If AL is low, pH will be affected by anything

introduced into the pool

• If AL is high, pH will be difficult to adjust (water

will scale)

Low Alkalinity (below 80 PPM) can cause:• Wide and rapid pH fluctuations

• Corrosion of pool or spa and equipment

• Skin / Eye Irritation

• Cloudy water

• Adding acid like Muriatic Acid will lower pH & Alkalinity


• When you add supplemental Chlorine products anticipate their different pHs, and anticipate Alkalinity effect

• Ideal level is 80-100 ppm with CHLORINE sanitizers such as Sodium, Calcium, or Lithium Hypochlorite

• Ideal level is 100-120 ppm with CHLORINE sanitizers such as Dichlor, Trichlor, Bromine, or Chlorine Gas

• Maximum must be below 160 PPM NOTE: Parts per million (ppm) is equivalent to milligrams per liter (mg/L).


• Photometric (1 ppm )• Titration (10 ppm )• Test Strips (40 ppm )

TOTAL ALKAINITY TEST METHODS (resolution)

ORDER OF pH and AL ADJUSTMENTS

• pH is most important factor• Affects all other chemical / balance parameters• Determines acidity of water • Measured on a scale from 0-14 • pH 7 is neutral• Below 7 is acidic (e.g. lemon juice and coke)• Above 7 is basic or alkaline (e.g. baking soda and

concrete)

pH

• pH in the ideal range will be comfortable for human eye at 7.5

• Pool water pH is acceptable from 7.2 - 7.8

• Ideal pH range is 7.4 - 7.6

• pH levels should be tested DAILY!

• High pH reduces Chlorine’s effectiveness

pH

pH

• pH meter (0.01 or 0.1)

• Photometric (0.1)

• pH comparator (0.2)

• Test Strips (0.2 or 0.3)

pH Testing Methods (resolution)

CALCIUM HARDNESS (CA)• Defined as the amount of Calcium Salts in water

(reported as Calcium Carbonate)

• Term Calcium Hardness used because hardness in tap water is due to Calcium

• Magnesium, barium & sulfate can contribute to Hardness

• Make-up water used to fill pool will vary in its calcium content depending on region of country / city or well water

• Ideal range is 200-400 PPM as CaCO3

• Maximum of 1000 PPM ?

CALCIUM HARDNESS (CA)

CALCIUM HARDNESS (CA)• Pool & spa water must have a certain amount of

Calcium

• Calcium Hardness, when outside optimal range, can allow corrosion or scaling

• Make-up water with high calcium is “hard water”

• Make-up water with low calcium is “soft water”

• Low water hardness allows corrosion of calcium rich surfaces such as concrete, plaster, & grout

• Photometric (1 PPM)

• Titration (20 PPM)

• Test Strips (over 50 PPM)

CALCIUM HARDNESSTEST METHODS (resolution)

TOTAL DISSOLVED SOLIDS(TDS)

• TDS = total of all dissolved material in water

• TDS value is contributed and influenced by ions

of calcium, magnesium, sulfate, chloride,

sodium, potassium, phosphate, nitrate, all ions;

Alkalinity; Cyanuric Acid; and other chemicals

present in water

TOTAL DISSOLVED SOLIDS(TDS)

HIGH TDS?High TDS levels ( over 1500 PPM) increases:

• Algae growth despite adequate sanitizer

• Corrosion despite water being otherwise balanced

• Cloudy water despite adequate filtration

• Eye and skin irritation

• Deposits on pool wall

• Salt pool TDS just add salt concentration: so 3500 PPM Sodium Chloride will add about 3500 TDS

TDS IN SALT POOLS

• TDS will increase in a salt pool over time

• Why? - chemicals are added, dirt and debris blow or wash

• Water evaporation from pool

• If TDS exceeds 1500 ppm of initial level (like 5000PPM) monitor TDS, clarity, and SI

• TDS at even 8000 ppm can work but requires effort to keep track of SI

TDS TESTING

• TDS levels should be tested MONTHLY using 1. Digital Conductivity meter ($20 - $900)

(can do thousands of tests)

2. Test strips ($0.30 to $0.50 per test)

• Maximum TDS is 1500 ppm over start-up TDS

• Some professionals find 5000 ppm TDS levels in pool water acceptable

TEMPERATURE

• Temperature is a water balance factor but difficult to control

• Pool water is normally 78 - 82◦ F • Spa water is normally 96 - 104◦ F• Test with digital or IR thermometer

•If pH goes up then Calcium Hardness and Alkalinity has to be kept at lower end (200 for CA & 80 for AL)

•Danger signs – pH above 7.8 and TA above 120

SI and RELATIONSHIP OF BALANCED WATER

SI (LSI)

SANITIZER AND DISINFECTANTS• The pool environment is constantly exposed to

new contaminants, two important considerations:

1. Sanitize water to kill microorganisms

2. Oxidize organic contaminants

SANITIZER AND DISINFECTANTS

• A disinfectant kills disease-causing organisms

• A sanitizer kills all microorganisms with impunity (USEPA 99.9% effective) i.e. , chlorine

• Oxidation refers to the “chemical reaction” that organic contaminants or waste products undergo

CHLORINE

• Chlorine is the most popular worldwide

sanitizer, disinfectant, algae killer and oxidizer

• Chlorine doubles as a sanitizer and oxidizer

• Chlorine is most effective under certain

conditions (pH)

CHLORINE

• Effective against a broad range of microorganisms

• Inactivation of pathogens depends on contact time

• In the United States, Health Departments require all public pools to be routinely tested for chlorine

GERM INACTIVATION TIME IN 1 ppm CHLORINATED WATER

GERM INACTIVATION TIME

E. Coli O157:H7Bacterium

Less than 1 minute

Hepatitis AVirus

About 16 minutes

GiardiaParasite

About 45 minutes

CryptosporidiumParasite

About 15300 minutes(10.6 days)pH 7.5, 77 F

CHLORINE SOURCES Salt Systems generate HOCl - or NaOCl equivalent

ChemicalName

ChemicalFormula

Form % Chlorine

Chlorine Gas

Cl2 Gas 100%

CalciumHypochlorite

Ca(OCl)2 Solid 65-70%

SodiumHypochlorite

NaOCl Liquid ~12%

ABOUT CHLORINE SOURCES

• Despite their chemical and physical differences, they form hypochlorous acid, or as more commonly known in the pool industry - Chlorine

• This change occurs when added to water

• Hypochlorous acid (HOCl) is the effective disinfecting agent

CHLORINE CHEMSTRY

• The sum of Hypochlorous acid (HOCI) and Hypochlorite ion (OCI ¯) is called free chlorine, and the chemical equation or relationship is:

HYPOCHLOROUS ACID REACTIONS

• Two chemical reactions impact Hypochlorous acid

as a disinfectant:

• FIRST REACTION hydroxide ion (OH¯)

• OH¯ is available in aqueous solution especially

when pH level is above 7 which causes

Hypochlorous acid to form Hypochlorite ion

HYPOCHLOROUS ACID REACTIONS

• Hypochlorite ion is less than one third as effective as a disinfectant as Hypochlorous acid

• The next slide shows the relationship between pH versus chlorine species (Hypochlorous acid and Hypochlorite ion)

pH VERSUS CHLORINE SPECIES

CHLORINE REACTION

• The SECOND REACTION is a series of chlorine reactions that occur with ammonia (NH3) and organic nitrogen compounds like proteins and amino acids to form chloramines

• Chloramines are less effective disinfectants

• Active chlorine can be transferred from inorganic chloramine to amine (organic) containing compounds

BREAKPOINT CHLORINATION

• Eliminating the combined chlorine and the ammonia / chloramine is called Breakpoint Chlorination

• In the pool industry its called “Shock” or “Super-Chlorination”

• Shock is required less frequently in Salt pools and depends on a variety of considerations

TOTAL CHLORINE

• Total chlorine = free chlorine + combined chlorine

• Free chlorine and total chlorine can be monitored by automated equipment and confirmed by poolside testing for swimmer protection

• DPD methods have become preferred for chlorine measurement

• DPD methods determine concentration by measuring intensity of color formed when chlorine reacts with DPD

• DPD-FAS Titration method determines chlorine by measuring amount of FAS Titrant needed to bleach out DPD-chlorine color formed

• State health departments accept DPD tests because they are quick, enjoy wide acceptance & EPA approved

DPD CHLORINE TESTING

• DPD Photometric Digital Meter (0.01)

• DPD-FAS Titrimetric (0.2)

• DPD Colorimetric Comparator (1 or 2)

• TMB Test Strip (0.2 but only detects free chlorine)

EPA ACCEPTEDCHLORINE TEST METHODS(FREE AND TOTAL)

• Combined chlorine = TC - FC

• Free chlorine = 1.58 ppm (FC)

• Total chlorine = 1.89 ppm (TC)

• Combined chlorine = 1.89 – 1.58 = 0.31 ppm

Combined chlorine is above the recommend level of 0.20 ppm and suggests pool needs to be shocked: in this example ( 10 X 0.31 = 3.1 ) this pool can be shocked by increasing the pool chlorine level by 3.1 ppm

TOTAL CHLORINE (TC) = FREE CHLORINE (FC) + COMBINED

CHLORINE

OTHER COMMON WATER QUALITY

PARAMETERS AND TREATMENT SOLUTIONS

OZONE GENERATION

• Ozone is negatively-charged oxygen atoms • Occurs naturally in the atmosphere, through the action of lightning• Non-toxic• Useful water purifier, used for decades in municipal water systems• Reduces the amount of chemicals needed to combat algae and

bacteria• Ozone has no effect on the pH balance, alkalinity or TDS of the pool

water, but it does NOT eliminate the use of chlorine• Breaks down immediately on contact with water-borne contaminants,

but does not combat algae formation on pool and spa walls

OZONE• Can reduce the use of biocides and algaecides in a

pool, it is not a complete solution

• Ozone generation involves the use of an ultraviolet (UV) or Corona Discharge (CD) unit which converts Oxygen (O2) to Ozone (O3)

• Advantages:• Reduces the use of sanitizing chemicals

• No effect on water balance

• Disadvantages:• Ineffective against algae

• High installation expense

PHOSPHATE

• Phosphorus is 0.12% of the earth’s crust

• Human bones and teeth contain calcium phosphate

• Phosphate is an essential nutrient for algae growth

• Phosphate testing is challenging below 0.2PPM (200 ppb)

HOW PHOSPHATE GETS IN WATER

• Runoff from lawns

• Rain water

• Bathers (sweat and urine)

• Pool treatment chemicals

• Blown in leaves and debris

CONTROL ALGAE BY CONTROLLING PHOSPHATE

• Increase swimming pool chlorine level if phosphate is present.

• “Flock” the phosphate with a phosphate flock salt and vacuum.

• Rain water is usually OK

SALTS THAT REMOVE PHOSPHATES

• Aluminum salts (inexpensive)Effective for levels above 1000 ppb.Does not remove phosphate below 100ppb.

HPO4-2 + Al+3 AlPO4↓ + H+

• Lanthanum salts (expensive)Effective for maintaining low levels of phosphate.Easier to use and apply than Aluminum salts.Can drop phosphate levels below 100 ppb.

HPO4-2 + La+3 LaPO4↓ + H+

LATHANUM SALTS(chloride and sulfate)

• Form a water insoluble Lanthanum Phosphate precipitate

• Easily removed by the pool filter media

• In high concentrations, salts will not cause cloudy water or staining of the pool

KEEP SALT POOLS PHOSPHATE FREE

• Test the water phosphate levels regularly• Avoid lawn/garden run-off from entering the pool• Remove leaves promptly • Keep phosphate below 120 ppb (0.12PPM)• Test the make-up water for phosphate (City water

may have as much as 1 PPM or 1000 PPB phosphates)

PHOSPHATE TESTING(resolution)

• Digital Photometric with reagent 0.01 PPM (or 10 PPB) resolution

• Test Strip with Comparator 0.1 PPM (or 100 PPB) resolution

• Ideally keep level below 0.1 PPM or 100 PPB• If Chlorine is maintained above 4PPM and CY

below 60PPM pool can tolerate 0.5PPM (500 PPM) phosphate without algae problem.

SALT• Salt in pool water also called salt chlorination • Dissolved salt (1,800–6,000 ppm) is needed for the

chlorination system• The chlorinator uses electrolysis to break down the

salt (NaCl +H2O = NaOH + HOCl). • The resulting chemical reaction eventually produces

Sodium HypoChlorite equivalent or NaOCl • Saltwater pool utilizes a chlorine generator

instead of direct addition of chlorine

COMMERCIAL CHLORINE SALT GENERATOR

• Device that produces chlorine from a mixture of salt and water (brine) through electrolysis

• Chlorine used is produced through the electrolysis of brine

• Electrolysis uses two electrically-charged electrodes:

• Anode (positively-charged)

• Cathode (negatively-charged) • Electrolyzing salt, the electrodes are contained in different chambers

because the result is chlorine gas and caustic soda, also known as lye, which should not be allowed to mix

• The chambers are separated by a special membrane allowing sodium ions and electricity to pass through it, but not chloride ions or water.

SALT• Anode chamber must periodically be refilled with water and salt

• The caustic soda can be re-used for adjusting the pool's pH balance

• A chlorine generator designed for a 25,000 – 30,000 gallon pool requires 45-50 pounds of salt, which must be replenished 2-4 times per year.

• A similar unit can generate Bromine by using Sodium Bromide instead of Sodium Chloride as a generating source

• Since chlorine and bromine generators produce water sanitizers continuously during operation, it is less necessary for chemicals to be added to the pool or spa water

• Equipment is expensive to buy and install

• In addition to regular testing, chlorine or bromine generators require salt level determination (Chloride or Bromide)

SALT TEST KITS (resolution)

• Photometric with SALT reagent (10 PPM)• TDS meters with Salt Algorithm (10 PPM) can be used but at least once a

year verify salt level with a second method (test strip or photometric)• Salt Test Strips (500 PPM) and Salt Titration Strips (100 PPM)• Most Salt System Manufacturers recommend accuracy of 500PPM for you

testing

• Cloudiness

• Caused by several factors:

1. Body-waste contamination

2. Non-organic suspended solids

3. Algae

4. Chemical imbalance (high alkalinity, high calcium)

• Turbidity is most commonly measured with a “turbidometric” meter – and is very accurate

• Can be tested with a photometer (less accurate)

TURBIDITY

• Pride in your work

• Customers expect it

• Health Departments require it

• Liability issues are bad for business

STRIVE FOR BEST RESULTS

Questions? Ivars Jaunakais – Chief Analytical Chemist

[email protected] www.sensafe.com

mailto:[email protected]

http://www.sensafe.com/

HELPFUL RESOURCES

• Book: Pool Chlorination Facts by Robert W. Lowry

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

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

• Book: The Pool Maintenance Manual by Terry Tamminen

• Internet: Florida Health Dept: http://www.doh.state.fl.us/Environment/water/swim/index.html

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

http://www.doh.state.fl.us/Environment/water/swim/index.html

http://www.cdc.gov/healthyswimming/

Education

Salt Pools 101 and the importance of constant testing